Interventional Cardiology

01 Coronary Anatomy & Variants

Coronary Arterial System

The coronary circulation arises from two ostia in the sinuses of Valsalva of the aortic root. The left main coronary artery (LMCA) arises from the left coronary sinus and typically courses 1-2 cm before bifurcating into the left anterior descending artery (LAD) and the left circumflex artery (LCx). In approximately 15-20% of patients, a ramus intermedius arises as a trifurcation branch between the LAD and LCx.

Left Anterior Descending (LAD): Courses in the anterior interventricular groove toward the apex. Gives off septal perforators (supply anterior two-thirds of the interventricular septum) and diagonal branches (D1, D2 — supply the anterolateral wall). The LAD supplies approximately 45-55% of the LV myocardium and is the most commonly diseased coronary artery. The first septal perforator is a landmark separating the left main from the proximal LAD.

Left Circumflex (LCx): Courses in the left atrioventricular groove, giving off obtuse marginal branches (OM1, OM2) that supply the lateral and posterolateral LV wall. In approximately 15% of patients the LCx is dominant (gives rise to the PDA). The LCx also gives off the left atrial circumflex branch and, in some patients, the SA nodal artery.

Right Coronary Artery (RCA): Arises from the right coronary sinus and courses in the right atrioventricular groove. Proximal branches include the conus branch (supplies the RV outflow tract), SA nodal artery (in ~55% of patients), and acute marginal branches (supply the RV free wall). The distal RCA gives rise to the posterior descending artery (PDA) in right-dominant circulation (~85% of the population) and the posterolateral branches.

Coronary Dominance

Coronary Segments (Modified AHA 15-Segment Model)

The coronary tree is divided into 15 segments for standardized reporting: RCA — proximal (1), mid (2), distal (3), PDA (4); Left Main (5); LAD — proximal (6), mid (7), distal (8), D1 (9), D2 (10); LCx — proximal (11), distal (12), OM1 (12a), OM2 (12b); Ramus intermedius (16 — if present). This segmental model is the basis of the SYNTAX score calculation.

Coronary Collaterals

Collateral circulation develops in response to chronic ischemia and high-grade stenoses. The Rentrop classification grades collateral filling: Grade 0 — no visible filling; Grade 1 — filling of side branches only; Grade 2 — partial filling of the epicardial artery; Grade 3 — complete filling of the epicardial artery. Well-developed collaterals (Rentrop 2-3) reduce infarct size and improve outcomes in CTO PCI.

Coronary Anomalies

Congenital coronary anomalies occur in ~1% of the general population. Anomalous origin from the opposite sinus (ACAOS) is the most clinically significant. An anomalous left main or LAD arising from the right coronary sinus with an interarterial course (between the aorta and pulmonary artery) carries risk of sudden cardiac death due to compression during exercise. An anomalous RCA from the left sinus is more common but less often clinically significant. Other anomalies include myocardial bridging (most commonly mid-LAD, prevalence 5-25% at angiography), coronary fistulae, and anomalous origin from the pulmonary artery (ALCAPA/ARCAPA).

Coronary Artery Territory & ECG Correlation

02 The Cardiac Catheterization Lab

Radiation Safety

The cath lab uses fluoroscopy and cineangiography (digital acquisition) to visualize coronary arteries and cardiac structures. Radiation exposure is measured in air kerma (Gy) — cumulative dose at the interventional reference point — and dose-area product (DAP, Gy·cm²). Key principles include: maintaining maximum distance from the source (inverse square law), using collimation to limit field size, minimizing fluoroscopy time, reducing frame rate (7.5-15 fps vs 30 fps), avoiding steep angulations (which increase tissue penetration depth), and using lead shielding. The sentinel event threshold for skin dose is 5 Gy (risk of deterministic skin injury). Operators should monitor cumulative air kerma in real time during complex cases (CTO, structural procedures).

Operator dose limits: The annual effective dose limit for radiation workers is 50 mSv/year (ALARA principle — As Low As Reasonably Achievable). Cumulative lifetime limit: 10 mSv × age in years. Occupational hazards include cataract formation (lens dose threshold ~500 mGy), thyroid cancer (wear thyroid shield), and left-sided brain tumors (reported in interventional cardiologists — wear lead cap). Recommended protective equipment: lead apron (0.5 mm Pb equivalent), thyroid shield, lead glasses (0.75 mm Pb), ceiling-mounted lead glass shield, under-table lead drape, and radiation dosimeter badges (collar and waist levels).

Vascular Access — Radial vs Femoral

Distal radial (snuffbox) access: Emerging technique with access at the anatomical snuffbox. Advantages include preserved antegrade radial flow, lower radial artery occlusion rates, and patient comfort (no wrist immobilization).

Catheters & Guidewires

Diagnostic catheters: Judkins Left (JL) — most common for LCA (JL 3.5 standard, JL 4.0 for dilated aortic root); Judkins Right (JR) — for RCA (JR 4.0 standard); Amplatz Left (AL) — alternative for LCA or anomalous RCA; Amplatz Right (AR) — for anomalous vessels; Multipurpose — for bypasses and anomalous coronaries. From radial access, Tiger, Jacky, or Ikari catheters can engage both left and right coronary arteries.

Guide catheters: 6 Fr is standard for PCI. EBU (Extra Backup) and XB (Xtra Backup) provide strong support for left coronary interventions. AL1/AL2 provide backup for RCA and anomalous vessels. Guide catheter selection is critical for adequate support in complex PCI — passive support (catheter shape), active support (deep seating), and guide extension catheters (GuideLiner, Trapliner) augment deliverability.

Coronary guidewires: 0.014-inch diameter is standard. Classified by tip stiffness — workhorse (Runthrough, BMW — 1 g tip load), intermediate (Pilot 50 — moderate steerability), stiff/CTO (Confianza Pro 9/12, Gaia 2nd/3rd — 9-12 g tip), and polymer-jacketed (Fielder XT, Gladius — for microchannel tracking). Wire tip shape, torque response, and prolapse resistance determine performance in different lesion types.

Vascular Closure Devices

Used after femoral access to achieve hemostasis and allow early ambulation. Types include: Collagen plug (Angio-Seal — deploys anchor and collagen sandwich), suture-mediated (Perclose ProGlide — pre-close technique for large-bore access up to 24 Fr), clip-based (StarClose), and extravascular sealant (Mynx). The pre-close technique with two Perclose devices deployed at 10 and 2 o'clock positions before sheath upsizing is standard for large-bore femoral access in TAVR and MCS.

03 Hemodynamic Assessment & Right Heart Catheterization

Right Heart Catheterization (Swan-Ganz)

A balloon-tipped pulmonary artery catheter (PAC) is advanced from venous access (internal jugular or femoral vein) through the RA → RV → PA and into the wedge position. Continuous monitoring provides: RA pressure, RV pressure, PA pressure, PCWP (pulmonary capillary wedge pressure), cardiac output, and mixed venous oxygen saturation (SvO2).

Normal Hemodynamic Values

Cardiac Output Measurement

Fick method: CO = VO2 / (CaO2 - CvO2), where VO2 is oxygen consumption (ideally measured, often assumed 125 mL/min/m² × BSA), CaO2 is arterial oxygen content, and CvO2 is mixed venous oxygen content. Most accurate when VO2 is directly measured. Thermodilution: Cold saline bolus injected via proximal port; temperature change detected at the PA thermistor generates a curve — CO is inversely proportional to the area under the curve. Less accurate in severe TR, low-output states, and intracardiac shunts.

Shunt Calculations

An intracardiac shunt is detected by an oxygen saturation step-up at the level of the shunt. A step-up of ≥7% at the atrial level (ASD), ≥5% at the ventricular level (VSD), or ≥5% at the PA level (PDA) is considered significant. Qp/Qs ratio = (SaO2 - SvO2) / (SpvO2 - SpaO2). A Qp/Qs ≥ 1.5 generally indicates a hemodynamically significant shunt warranting closure.

Valve Gradient Assessment

Aortic stenosis: Simultaneous measurement of LV and aortic pressures yields the peak-to-peak gradient (catheter gradient) and mean gradient. The Gorlin formula calculates valve area: AVA = CO / (44.3 × SEP × HR × √mean gradient). A Gorlin AVA ≤ 1.0 cm² with mean gradient ≥ 40 mmHg confirms severe AS. In low-flow, low-gradient AS, dobutamine stress hemodynamics help distinguish true-severe from pseudo-severe AS.

Mitral stenosis: The PCWP-to-LV diastolic gradient defines mitral valve gradient. MVA is calculated using the Gorlin formula or estimated by the pressure half-time method on echo. MVA ≤ 1.5 cm² is moderate; ≤ 1.0 cm² is severe.

Pulmonary Hypertension Assessment

Right heart catheterization is the gold standard for diagnosing pulmonary hypertension. Pre-capillary PH: mPAP >20 mmHg, PCWP ≤15 mmHg, PVR ≥3 Wood units. Post-capillary PH (group 2): mPAP >20 mmHg, PCWP >15 mmHg. Combined pre- and post-capillary PH: mPAP >20 mmHg, PCWP >15 mmHg, PVR ≥3 Wood units. Vasoreactivity testing with inhaled nitric oxide (10-20 ppm), IV epoprostenol, or IV adenosine is performed in idiopathic PAH — a positive response (≥10 mmHg decrease in mPAP to ≤40 mmHg with maintained or increased CO) identifies candidates for calcium channel blocker therapy.

PVR calculation: PVR = (mPAP - PCWP) / CO. Normal PVR is <3 Wood units (240 dynes·s/cm&sup5;). Conversion: 1 Wood unit = 80 dynes·s/cm&sup5;. In pre-TAVR assessment, PVR >5 Wood units raises concern for prohibitive surgical risk and may warrant vasodilator challenge to assess reversibility.

Intracardiac Shunt Detection — Oximetry Run

A complete oximetry run involves sampling oxygen saturations from the SVC, IVC, RA, RV, PA, LA (if accessible), LV, and aorta. Significant step-ups indicate left-to-right shunting at the corresponding level:

04 Diagnostic Coronary Angiography

Standard Angiographic Views

Stenosis Grading & Quantitative Coronary Angiography (QCA)

Visual estimation of diameter stenosis remains standard but has significant interobserver variability. QCA provides objective measurements: reference vessel diameter (RVD), minimum lumen diameter (MLD), percent diameter stenosis (%DS), and lesion length. The threshold for "significant" stenosis is generally ≥70% diameter stenosis for epicardial coronary arteries and ≥50% for the left main.

TIMI Flow Grade

TIMI Myocardial Perfusion Grade (TMPG)

Assesses microvascular perfusion independent of epicardial flow: TMPG 0 — no myocardial blush; TMPG 1 — slow entry, staining persists on next injection; TMPG 2 — slow entry and exit; TMPG 3 — normal entry and exit. TMPG 3 after primary PCI is associated with the lowest mortality.

SYNTAX Score

The SYNTAX (Synergy Between PCI with Taxus and Cardiac Surgery) score is an angiographic tool that quantifies the complexity of coronary artery disease based on lesion location, severity, bifurcation involvement, calcification, tortuosity, thrombus, and vessel characteristics across all segments. Low SYNTAX (≤22): PCI and CABG equivalent; Intermediate (23-32): discuss with Heart Team; High (≥33): CABG preferred. The SYNTAX II score incorporates clinical variables (age, LVEF, CrCl, COPD, PVD) to improve prognostic accuracy.

05 Percutaneous Coronary Intervention (PCI)

Evolution of Coronary Stents

PCI Technique — Step-by-Step

1. Guide catheter engagement — Coaxial alignment with the coronary ostium; adequate backup support. 2. Wiring the lesion — Advance a 0.014" guidewire across the stenosis into the distal vessel. 3. Predilation — Compliant balloon (sized 1:1 to reference vessel or slightly undersized) inflated across the lesion to create a channel for stent delivery. 4. Stent deployment — Select stent diameter to match reference vessel (by QCA or intravascular imaging); stent length should cover the lesion with 2-3 mm margin on each side. Inflate at nominal pressure (8-12 atm) for deployment. 5. Post-dilation — Non-compliant balloon (NC) inflated at high pressure (14-20 atm) to ensure full stent expansion and apposition; sized 1:1 to the reference vessel. 6. Final angiography — Confirm TIMI 3 flow, no dissection, no residual stenosis, good distal runoff.

Stent Sizing Principles

Stent diameter should match the distal reference vessel diameter by angiography (or the media-to-media diameter by IVUS/OCT). Stent undersizing leads to malapposition (risk of stent thrombosis); oversizing leads to edge dissection and vessel injury. IVUS-guided PCI targets minimum stent area (MSA) ≥ 5.5 mm² in non-left-main vessels and ≥ 8.0 mm² in the left main. OCT criteria include: stent expansion ≥80% of reference lumen area, no edge dissection >200 μm, and complete stent apposition.

Kissing Balloon Inflation

Simultaneous inflation of two balloons in the main vessel and side branch at bifurcation stenting. Purpose: correct carina shift, maintain side branch patency, optimize stent apposition at the bifurcation. POT-side-POT (proximal optimization technique) is an alternative strategy: short NC balloon inflated in the proximal main vessel to flare the stent, followed by wire rewiring and kissing balloon or POT.

Specialty Balloons

Guide Extension Catheters

GuideLiner (Teleflex) and Guidezilla (Boston Scientific) are rapid-exchange coaxial guide extension catheters that telescope within the guide catheter and extend ~25 cm into the coronary artery. They provide enhanced backup support for device delivery in tortuous anatomy, calcified lesions, and distal lesions. The "trapping" technique (inflating a balloon in the guide to trap a wire) allows wire exchange through the extension catheter without losing position. Guide extensions also serve as conduits for delivering thrombus aspiration catheters, coils, and covered stents to distal locations.

06 STEMI Intervention & Cardiogenic Shock

Primary PCI for STEMI

Primary PCI is the preferred reperfusion strategy for STEMI when it can be performed within 120 minutes of first medical contact (door-to-balloon time target <90 minutes at PCI-capable hospitals; <120 minutes with transfer). Emergency Primary PCI achieves TIMI 3 flow in >90% of cases, compared to ~50-60% with fibrinolysis. Radial access is preferred (MATRIX trial — reduced bleeding and mortality in STEMI).

Culprit Lesion PCI vs Complete Revascularization

In STEMI with multivessel disease, culprit-lesion-only PCI is the standard acute approach. The COMPLETE trial demonstrated that staged complete revascularization of non-culprit lesions (during index hospitalization or within 45 days) reduced the composite of cardiovascular death and MI compared to culprit-only PCI. FFR-guided non-culprit PCI is supported by the DANAMI-3-PRIMULTI and Compare-Acute trials. Non-culprit PCI should generally not be performed at the time of primary PCI unless there is hemodynamic instability, ongoing ischemia, or cardiogenic shock.

Thrombus Management

Large thrombus burden is common in STEMI. Routine aspiration thrombectomy is no longer recommended (TOTAL, TASTE trials — no mortality benefit, increased stroke risk). Aspiration may be considered as a bailout strategy for massive thrombus burden with TIMI 0-1 flow despite wire crossing. GP IIb/IIIa inhibitors (abciximab, eptifibatide) may be used as bailout for large thrombus burden or no-reflow.

Cardiogenic Shock — STEMI

Emergency Cardiogenic shock complicates 5-10% of STEMI cases and carries 40-50% in-hospital mortality. The SHOCK trial established early revascularization (PCI or CABG within 6 hours) as the standard of care — 6-month mortality reduction from 63% to 50%. Key management principles:

Hemodynamic support: Vasopressors (norepinephrine preferred over dopamine — SOAP II trial), inotropes (dobutamine, milrinone), and mechanical circulatory support (MCS) — see Section 16. The SCAI shock classification (stages A-E) guides escalation of support. Stage C (classic shock: hypotension, CI <2.2, PCWP >15, lactate rising) should prompt MCS consideration. Stage D (deteriorating) and Stage E (extremis — refractory cardiac arrest) require emergent MCS or ECMO.

Mechanical Complications of STEMI

Mechanical complications typically occur 2-7 days post-MI (earlier with reperfusion). All are surgical emergencies:

Papillary muscle rupture most commonly involves the posteromedial papillary muscle (single blood supply from PDA — affected in inferior MI) rather than the anterolateral papillary muscle (dual supply from LAD and LCx). Complete rupture is rapidly fatal without surgical intervention. Partial rupture may present subacutely.

07 Complex PCI — CTO, Bifurcation & Left Main

Chronic Total Occlusion (CTO) PCI

A CTO is defined as a coronary occlusion with TIMI 0 flow for ≥3 months. CTO PCI is among the most technically demanding coronary interventions. The hybrid algorithm guides strategy selection based on four angiographic features: (1) ambiguity of the proximal cap, (2) lesion length (>20 mm), (3) presence of an interventional collateral for retrograde access, and (4) quality of the distal vessel target.

Antegrade wire escalation (AWE): First-line strategy for short CTOs (<20 mm) with a clear proximal cap. Escalation from soft-tipped wires through intermediate to stiff, tapered CTO wires (Confianza Pro 12, Gaia 3rd). Antegrade dissection re-entry (ADR): For long CTOs (>20 mm). A knuckled polymer wire is advanced into the subintimal space, and a re-entry device (Stingray balloon) redirects back into the true lumen distally. Retrograde approach: A wire is passed through a collateral channel (septal or epicardial) to the distal cap of the CTO. Techniques include reverse CART (Controlled Antegrade and Retrograde subintimal Tracking) — the most common retrograde strategy.

CTO PCI success rates at experienced centers exceed 85-90%. The J-CTO score predicts procedural difficulty: 0 = easy, 1 = intermediate, 2 = difficult, ≥3 = very difficult. Variables scored: blunt proximal cap, calcification, bending >45°, occlusion length >20 mm, and prior failed attempt.

CTO Crossing Strategies — Detailed

Reverse CART (Controlled Antegrade and Retrograde subintimal Tracking): The most common retrograde crossing technique. An antegrade knuckle wire creates a subintimal space; the retrograde wire punctures into this space, connecting the retrograde and antegrade paths. A balloon is inflated over the antegrade wire to enlarge the connection point, allowing the retrograde wire to cross into the antegrade guide catheter. The retrograde wire is then externalized (pulled through the antegrade guide) and used as a rail for stent delivery.

Bifurcation PCI

Bifurcation lesions account for 15-20% of PCI. The Medina classification describes involvement of the proximal main vessel, distal main vessel, and side branch (1 = ≥50% stenosis, 0 = <50%): e.g., Medina 1,1,1 = all three segments diseased; Medina 1,1,0 = main vessel only.

Provisional stenting is the default strategy: stent the main vessel, then assess the side branch. If the side branch has ≥75% stenosis, TIMI <3 flow, or threatened territory >10% of myocardium, perform side branch intervention (wire, balloon, or T-stent). Two-stent strategies are reserved for true bifurcations with large side branches:

Left Main PCI

Left main PCI is an alternative to CABG in selected patients. The EXCEL trial (5-year follow-up) showed no significant difference in the composite of death, MI, or stroke between PCI and CABG for left main disease with low-intermediate SYNTAX scores (≤32), though CABG had lower rates of repeat revascularization. The NOBLE trial favored CABG at 5 years, driven by higher non-procedural MI and repeat revascularization with PCI. Current guidelines recommend Heart Team discussion for all left main decisions.

Technical considerations: Distal left main bifurcation (most common location) is treated based on LCx ostial involvement — provisional stenting if LCx not significantly diseased, DK-crush or culotte if both LAD and LCx require stenting. Intravascular imaging is strongly recommended (class IIa). IVUS MSA targets: ≥8 mm² in the left main body, ≥7 mm² at the polygon of confluence, ≥6 mm² in the LAD ostium, ≥5 mm² in the LCx ostium.

Calcified Lesion Modification

Severe calcification impairs stent delivery and expansion. Calcium modification techniques:

08 Intravascular Imaging & Coronary Physiology

Intravascular Ultrasound (IVUS)

IVUS uses a miniaturized ultrasound transducer (20-60 MHz) on a catheter to produce cross-sectional images of the vessel wall. Resolution: axial ~100 μm, lateral ~200 μm. IVUS penetrates through calcium (unlike OCT) and visualizes the full vessel wall thickness. Grayscale IVUS identifies plaque burden, lumen area, external elastic membrane (EEM) area, and stent expansion. Virtual histology (VH-IVUS) uses radiofrequency backscatter analysis to characterize plaque composition (fibrous, fibrofatty, necrotic core, dense calcium).

IVUS-guided PCI targets: MSA ≥5.5 mm² (non-left main), MSA ≥8.0 mm² (left main body), no edge dissection involving the media, stent expansion ≥80% of reference lumen, and absence of geographic miss (lesion extending beyond stent edges). The ULTIMATE trial and ADAPT-DES study confirmed IVUS guidance reduces MACE compared to angiography alone.

Optical Coherence Tomography (OCT)

OCT uses near-infrared light (1,300 nm wavelength) to produce ultra-high-resolution images of the vessel wall. Resolution: axial ~10-15 μm (10x better than IVUS), lateral ~20-40 μm. Limitation: poor tissue penetration (~1-2 mm) — cannot see through calcium or deep plaque; requires blood clearance (contrast flush). OCT excels at identifying: thin-cap fibroatheroma (TCFA) — cap thickness <65 μm overlying a lipid-rich core (vulnerable plaque); stent malapposition (strut-to-intima distance >strut thickness + polymer); stent underexpansion; edge dissection (flap >200 μm or involving the media); thrombus (red vs white); and neoatherosclerosis (lipid-laden intima within stents).

The ILUMIEN IV trial demonstrated that OCT-guided PCI achieved larger MSA and lower rates of stent underexpansion compared to angiography-guided PCI, though the primary clinical endpoint was not significantly different at 2 years.

Fractional Flow Reserve (FFR)

FFR is the ratio of distal coronary pressure (Pd) to aortic pressure (Pa) at maximal hyperemia (adenosine 140 μg/kg/min IV or IC bolus). FFR = Pd/Pa. An FFR ≤0.80 indicates a hemodynamically significant stenosis warranting revascularization. Landmark trials:

FAME — FFR-guided PCI vs angiography-guided PCI in multivessel disease: FFR guidance reduced death, MI, and repeat revascularization at 1 year. FAME 2 — FFR-guided PCI + OMT vs OMT alone for FFR ≤0.80: PCI reduced urgent revascularization (trial stopped early); no mortality difference at 5 years. DEFER — Deferring PCI when FFR >0.75 was safe at 15-year follow-up.

Non-Hyperemic Pressure Ratios (NHPR)

iFR (instantaneous wave-free ratio) and RFR (resting full-cycle ratio) measure the Pd/Pa ratio during a specific diastolic window (iFR) or the lowest Pd/Pa during the entire cardiac cycle (RFR), without requiring hyperemia. An iFR/RFR ≤0.89 indicates hemodynamic significance. The DEFINE-FLAIR and iFR-SWEDEHEART trials demonstrated non-inferiority of iFR-guided revascularization compared to FFR-guided revascularization at 1 year.

Coronary Flow Reserve (CFR) & Index of Microcirculatory Resistance (IMR)

CFR is the ratio of hyperemic to resting coronary flow velocity (measured by Doppler wire) or transit time (thermodilution). CFR <2.0 indicates impaired flow reserve, which may reflect epicardial stenosis, microvascular disease, or both. IMR = Pd × transit time at hyperemia; IMR ≥25 indicates microvascular dysfunction. In STEMI, elevated IMR post-PCI predicts larger infarct size and worse LV recovery. Combined assessment of FFR + CFR + IMR allows differentiation between epicardial disease, microvascular disease, and normal hemodynamics — the endotype classification guides targeted therapy.

Angioscopy & Near-Infrared Spectroscopy (NIRS)

NIRS (TVC Imaging System, Infraredx/Lipid-Rich Plaque) identifies lipid-core plaques within the vessel wall by measuring the absorption of near-infrared light. A lipid core burden index (LCBI) at the maximal 4 mm segment (maxLCBI4mm) ≥400 is associated with increased risk of periprocedural MI during PCI and future MACE (LRP study). NIRS is often combined with IVUS on a single catheter platform (Makoto, TVC) for simultaneous structural and compositional assessment.

09 Acute Coronary Syndromes — Antithrombotic Management

NSTEMI — Timing of Catheterization

Risk stratification guides timing: Immediate (<2 hours) — hemodynamic instability, ongoing chest pain despite medical therapy, life-threatening arrhythmias, mechanical complications. Early (<24 hours) — GRACE score >140, dynamic ST/T changes, rise/fall in troponin (TIMACS trial — early invasive strategy reduced the composite of death, MI, stroke in high-risk patients). Delayed invasive (24-72 hours) — lower-risk patients without high-risk features. Selective invasive (ischemia-guided) — low-risk patients with no recurrent symptoms and negative stress test.

Antiplatelet Therapy

DAPT Duration

Standard: 12 months of DAPT (aspirin + P2Y12 inhibitor) after ACS regardless of stent type. Extended (>12 months): Consider in high ischemic risk / low bleeding risk (PEGASUS-TIMI 54 — ticagrelor 60 mg BID beyond 12 months reduced CV events). Shortened (3-6 months): Consider in high bleeding risk (TWILIGHT — ticagrelor monotherapy after 3 months of DAPT reduced bleeding without increasing ischemic events; STOPDAPT-2 — 1 month DAPT followed by clopidogrel monotherapy). The DAPT score (≥2 favors prolonged DAPT; <2 favors shortened) incorporates: age, diabetes, smoking, prior MI/PCI, stent diameter <3 mm, CHF/LVEF <30%, paclitaxel-eluting stent, and vein graft PCI.

Anticoagulation in ACS

Unfractionated heparin (UFH): Standard during PCI — 70-100 U/kg bolus (50-70 U/kg if GP IIb/IIIa used); target ACT 250-350 s (200-250 s with GP IIb/IIIa). Bivalirudin: Direct thrombin inhibitor — 0.75 mg/kg bolus + 1.75 mg/kg/h infusion; alternative to UFH, especially in high bleeding risk patients (HORIZONS-AMI, EUROMAX). No need for ACT monitoring. Enoxaparin: LMWH — 0.5-1 mg/kg SC or IV; if used pre-cath, additional 0.3 mg/kg IV bolus if last dose >8 hours ago. Fondaparinux: Factor Xa inhibitor — 2.5 mg SC daily; if used pre-cath, must supplement with UFH during PCI (OASIS-5 — catheter thrombosis risk without supplemental UFH).

GP IIb/IIIa Inhibitors

Routine upstream use is no longer recommended. Bailout use is appropriate for: large thrombus burden, no-reflow, threatened vessel closure, or slow flow. Agents: Abciximab (0.25 mg/kg bolus + 0.125 μg/kg/min × 12 h), eptifibatide (180 μg/kg double bolus + 2 μg/kg/min × 18-24 h), tirofiban (25 μg/kg bolus + 0.15 μg/kg/min × 18-24 h). Eptifibatide and tirofiban require dose adjustment in renal impairment.

10 Stent Complications & No-Reflow

In-Stent Restenosis (ISR)

ISR is defined as ≥50% diameter stenosis within the stent or within 5 mm of the stent edges. It is caused by neointimal hyperplasia (smooth muscle cell proliferation and extracellular matrix deposition) and, in late ISR, neoatherosclerosis. ISR rates: BMS 20-30% at 1 year; first-gen DES 5-10%; second/third-gen DES 3-5%. The Mehran classification describes ISR patterns: Type I (focal, ≤10 mm), Type II (intra-stent, >10 mm), Type III (proliferative, extending beyond stent edges), Type IV (total occlusion).

Treatment algorithm for ISR: Step 1 — Perform IVUS or OCT to identify mechanical causes (stent underexpansion is the most common correctable cause). Step 2 — If underexpanded, high-pressure NC balloon inflation (≥20 atm) or IVL to crack calcified plaque restricting expansion. Step 3 — If adequately expanded, treat the neointimal tissue: Drug-eluting balloon (DEB) — preferred for focal ISR (AGENT IDE trial — sirolimus DEB showed 76% freedom from TLR at 12 months); DES (different drug) — preferred for diffuse ISR (RIBS IV — everolimus DES superior to DEB for diffuse ISR); Laser atherectomy or rotational atherectomy — for severely underexpanded stents with circumferential calcium that cannot be dilated with balloons.

Stent fracture is an underrecognized cause of ISR and stent thrombosis. Risk factors: long stents, hinge points (RCA), overlapping stents, and right coronary artery location. Diagnosis: fluoroscopic "gap" in stent struts, confirmed by IVUS/OCT showing strut discontinuity. Treatment: additional DES deployment across the fracture site.

Stent Thrombosis

Stent thrombosis is a catastrophic event presenting as acute MI with high mortality (20-45%). The Academic Research Consortium (ARC) classification defines certainty (definite, probable, possible) and timing:

Risk factors: premature DAPT discontinuation (most important modifiable factor), stent underexpansion, edge dissection, residual stenosis, bifurcation stenting, long stents, small vessel diameter, diabetes, renal failure, and low LVEF. Treatment: emergent PCI with IVUS/OCT to identify and correct the mechanical cause.

Saphenous Vein Graft (SVG) Intervention

SVG PCI carries higher risk of distal embolization and no-reflow due to the friable, degenerated plaque within vein grafts. The SAFER trial demonstrated that a distal embolic protection device (EPD) — FilterWire or SpiderFX — reduces 30-day MACE by 42% during SVG PCI. Key principles: Always use embolic protection (class I recommendation); avoid direct stenting without predilation (risk of distal embolization from bulky plaque); use DES over BMS (lower restenosis rates); keep stent margins away from the aortic anastomosis; and avoid GP IIb/IIIa inhibitors as first-line (no proven benefit in SVG PCI; increase bleeding). For severely degenerated SVGs with diffuse disease, consider native vessel PCI (including CTO PCI of the native vessel) as an alternative to SVG intervention.

Coronary Perforation

The Ellis classification grades perforation severity:

No-Reflow Phenomenon

No-reflow is defined as TIMI ≤2 flow in the absence of epicardial obstruction (dissection, thrombus, spasm, or residual stenosis). It is caused by distal embolization of thrombus/plaque debris, microvascular spasm, and reperfusion injury. Occurs in 2-5% of PCI and up to 10-30% of primary PCI for STEMI. Treatment: Intracoronary adenosine (100-200 μg boluses), nitroprusside (100-200 μg IC), verapamil (100-200 μg IC), nicardipine (200 μg IC), and epinephrine (50-200 μg IC for refractory cases). GP IIb/IIIa inhibitors may be used if thrombus burden is suspected. Distal protection devices (FilterWire, SpiderFX) are recommended for SVG interventions (SAFER trial) but not for native coronary PCI.

11 Transcatheter Aortic Valve Replacement (TAVR)

Indications & Evidence

TAVR is approved for symptomatic severe aortic stenosis across the surgical risk spectrum. Landmark trials by risk category:

Device Platforms

Edwards SAPIEN 3 / SAPIEN 3 Ultra: Balloon-expandable bovine pericardial valve; cobalt-chromium frame; sizes 20, 23, 26, 29 mm; outer skirt to reduce paravalvular leak; 14-16 Fr eSheath (expandable). Medtronic CoreValve Evolut R / Evolut PRO / Evolut FX: Self-expanding porcine pericardial valve; nitinol frame; sizes 23, 26, 29, 34 mm; supra-annular leaflet position; recapturable and repositionable; 14 Fr InLine sheath.

CT Planning for TAVR

Multidetector CT is the gold standard for pre-procedural planning: Annular sizing — perimeter-derived diameter (most accurate), area-derived diameter, and mean diameter determine valve size; Coronary heights — distance from annulus to left and right coronary ostia (risk of coronary obstruction if <12 mm with SAPIEN or <10 mm with self-expanding); Sinus of Valsalva dimensions — small sinuses increase coronary obstruction risk; Calcium scoring — valve and LVOT calcium distribution predict paravalvular leak, conduction disturbance, and annular rupture risk; Iliofemoral access — minimum diameter ≥5.5 mm for current-generation devices; tortuosity and calcification assessment.

TAVR Access Routes

Transfemoral (TF): Preferred approach (>95% of cases); lowest morbidity. Alternative routes (when TF not feasible): transaxillary/subclavian (surgical cutdown or percutaneous), transaortic (mini-sternotomy), transapical (left thoracotomy — largely abandoned due to higher mortality), transcaval (IVC-to-aorta puncture — emerging), transcarotid.

TAVR Procedural Steps

1. Access and sheath placement: Percutaneous femoral access with pre-close (2 Perclose ProGlide devices); eSheath (Edwards) or InLine sheath (Medtronic) advanced to the descending aorta. 2. Crossing the aortic valve: A straight-tipped wire crosses the stenotic aortic valve; exchanged for an extra-stiff guidewire (Safari, Lunderquist, Confida) positioned in the LV apex. 3. Balloon aortic valvuloplasty (BAV): Optional predilation with a 20-25 mm balloon under rapid ventricular pacing (180-220 bpm) to create a passage for the TAVR device. Increasingly, BAV is deferred ("direct implantation"). 4. Valve deployment: Balloon-expandable (SAPIEN) — positioned at the annular level under fluoroscopy and rapid pacing, then inflated with precise volume to deploy the valve. Self-expanding (Evolut) — unsheathed gradually; repositionable; no rapid pacing required. 5. Assessment: Aortography and TEE/TTE to assess paravalvular leak, valve position, coronary patency, and hemodynamics. Post-dilation with a larger balloon if significant PVL. 6. Closure: Tighten Perclose sutures; angiography to confirm hemostasis.

Valve-in-Valve TAVR

TAVR within a previously implanted surgical bioprosthetic valve that has degenerated (stenosis or regurgitation). Sizing is based on the true internal diameter (ID) of the surgical valve (available in manufacturer charts). Key considerations: risk of patient-prosthesis mismatch (PPM) — small surgical valves (≤21 mm) may result in high residual gradients after VIV; coronary obstruction risk is higher with VIV (especially with externally mounted leaflets that can cover the coronary ostia upon TAVR deployment); BASILICA technique (Bioprosthetic or native Aortic Scallop Intentional Laceration to prevent Iatrogenic Coronary Artery obstruction) — intentional electrosurgical laceration of a bioprosthetic leaflet before TAVR to maintain coronary flow.

TAVR Complications

12 Mitral & Tricuspid Interventions

Transcatheter Edge-to-Edge Repair (TEER) — MitraClip / PASCAL

TEER creates a tissue bridge between the anterior and posterior mitral leaflets, mimicking the surgical Alfieri edge-to-edge repair. The MitraClip (Abbott) is delivered via transseptal puncture from the femoral vein, guided by TEE and fluoroscopy.

COAPT trial: In patients with heart failure (LVEF 20-50%) and severe secondary (functional) mitral regurgitation on maximally tolerated GDMT, TEER reduced heart failure hospitalizations by 47% and all-cause mortality by 29% at 2 years compared to GDMT alone. Key enrollment criterion: effective regurgitant orifice area (EROA) ≥30 mm² and LVEDV ≤200 mL (disproportionate MR concept). MITRA-FR trial: Did not show benefit of TEER in secondary MR — different patient population (proportionate MR, larger ventricles, lower EROA threshold).

Primary (degenerative) MR: TEER is indicated for patients with symptomatic severe primary MR who are at prohibitive or high surgical risk. The EVEREST II trial showed MitraClip was less effective than surgery for reducing MR but had superior safety.

PASCAL device: The PASCAL system (Edwards Lifesciences) is a newer TEER platform with a central spacer that fills the regurgitant orifice and broad paddles for leaflet grasping, plus independent clasping of each leaflet. It may be advantageous for wide flail gaps and complex anatomy where MitraClip grasping is difficult. The CLASP IID/IIF trials evaluated PASCAL in both degenerative and functional MR.

Mitral Annuloplasty Devices

Cardioband (Edwards): Percutaneous direct annuloplasty — anchors deployed along the posterior mitral annulus via transseptal approach under TEE guidance; a contraction wire reduces annular dimensions, similar to surgical annuloplasty. Approved for functional MR in Europe. Carillon (Cardiac Dimensions): Indirect annuloplasty via the coronary sinus — a nitinol device placed in the coronary sinus compresses the posterior mitral annulus to reduce annular dimensions and MR. Limitation: may impinge on the LCx artery.

Transcatheter Mitral Valve Replacement (TMVR)

Multiple devices in development or early clinical use (Tendyne, Intrepid/APOLLO, Evoque) for patients not amenable to TEER. Challenges include: large device profile, LVOT obstruction risk, leaflet interaction, paravalvular leak, and need for transseptal or transapical access. Valve-in-valve TMVR for failed surgical bioprostheses (using SAPIEN 3) is established with good outcomes.

Percutaneous Balloon Mitral Valvuloplasty (PBMV)

Indicated for symptomatic moderate-severe rheumatic mitral stenosis with favorable valve morphology. The Wilkins score (0-16) assesses leaflet mobility, thickening, calcification, and subvalvular disease — a score ≤8 predicts good results. Contraindications: moderate-severe MR, left atrial thrombus, severe calcification. Performed via transseptal puncture using an Inoue balloon. Success defined as MVA >1.5 cm² and ≤1+ MR increase.

Tricuspid Interventions

Severe tricuspid regurgitation (TR) is increasingly recognized as an important contributor to morbidity and mortality. Transcatheter options are expanding:

TriClip (TEER for tricuspid): The TRILUMINATE Pivotal trial demonstrated TEER reduced TR severity at 1 year compared to medical therapy, though the primary endpoint of composite of death, tricuspid surgery, heart failure hospitalization, or improvement in quality of life narrowly missed superiority. PASCAL tricuspid TEER: Similar edge-to-edge concept with a broader clasping mechanism. Transcatheter tricuspid valve replacement (TTVR): Devices in trial include EVOQUE (heterotopic — placed in the IVC/SVC to reduce TR regurgitant volume) and orthotopic replacement systems. The TRISCEND II trial (EVOQUE) showed significant TR reduction. Cardioband: Percutaneous annuloplasty device delivering anchors along the tricuspid annulus; provides annular reduction similar to surgical ring annuloplasty.

13 Left Atrial Appendage Closure

Rationale

The left atrial appendage (LAA) is the source of >90% of thrombi in non-valvular atrial fibrillation. LAA closure (LAAC) provides an alternative to long-term oral anticoagulation (OAC) for stroke prevention in patients with AF who have contraindications to OAC or high bleeding risk.

WATCHMAN Device

The WATCHMAN (Boston Scientific) is a nitinol frame with a permeable polyester fabric cap that is delivered via transseptal puncture and deployed in the LAA ostium. The PROTECT-AF trial demonstrated non-inferiority of WATCHMAN to warfarin for the composite of stroke, systemic embolism, and cardiovascular death at 5-year follow-up, with a significant reduction in hemorrhagic stroke and all-cause mortality. The PREVAIL trial confirmed non-inferiority for ischemic stroke at 5 years. The WATCHMAN FLX (next generation) has improved sealing, lower device-related thrombus, and higher procedural success (>98%).

Amulet Device

The Amulet (Abbott) is a dual-seal device with a lobe and disc that provides two levels of LAA sealing. The Amulet IDE trial demonstrated non-inferiority to WATCHMAN for safety and efficacy at 18 months, with numerically lower rates of peri-device leak.

Lariat Device (Epicardial LAA Ligation)

The Lariat system uses a combined epicardial and endocardial approach to deliver a suture loop around the LAA. A magnet-tipped wire is placed in the LAA via transseptal puncture, and a corresponding epicardial wire is advanced through a subxiphoid pericardial puncture. The Lariat snare is then delivered over the epicardial wire to lasso and ligate the LAA base. Advantages: no implanted device; complete LAA exclusion. Limitations: requires pericardial access (not feasible with prior cardiac surgery or pericardial adhesions), risk of pericarditis, pericardial effusion, and incomplete closure. The device has fallen out of favor relative to endocardial devices (WATCHMAN, Amulet).

Post-Implant Management

Standard protocol: DAPT (aspirin + clopidogrel) or short-term anticoagulation (45 days to 6 months) post-implant until device endothelialization, confirmed by TEE showing complete LAA seal and absence of device-related thrombus. Then transition to aspirin monotherapy or discontinuation of all antithrombotic therapy based on individual risk.

Patient Selection for LAAC

LAAC is most appropriate for AF patients with: CHA2DS2-VASc ≥2 (stroke risk warrants OAC), HAS-BLED ≥3 (high bleeding risk), and specific contraindications to long-term OAC (prior life-threatening bleed, intracranial hemorrhage, end-stage renal disease on dialysis, recurrent falls, or labile INR). Current guidelines give LAAC a class IIb recommendation for patients with AF unsuitable for long-term anticoagulation.

14 ASD/PFO Closure & Septal Ablation

Patent Foramen Ovale (PFO) Closure

PFO is present in ~25% of the general population. The association between PFO and cryptogenic stroke led to pivotal closure trials:

Current indications for PFO closure: age 18-60, cryptogenic stroke (thorough workup excluding other causes), PFO with moderate-large shunt or atrial septal aneurysm (ASA), and high RoPE score (Risk of Paradoxical Embolism — higher score indicates greater probability that PFO is causal). Post-closure: DAPT for 1-6 months, then aspirin alone for 5 years.

Atrial Septal Defect (ASD) Closure

Transcatheter closure is standard for secundum ASD with adequate rims (≥5 mm on all borders except the aortic rim). Devices: Amplatzer Septal Occluder (most widely used), GORE Cardioform. Indications: Qp/Qs ≥1.5, right heart enlargement, or paradoxical embolism. Primum, sinus venosus, and coronary sinus ASDs require surgical closure. Sizing is guided by TEE and/or intracardiac echocardiography (ICE). Complications: device embolization (1-2%), erosion (<0.1%), residual shunt, AF, air embolism.

Alcohol Septal Ablation (ASA)

Percutaneous treatment for hypertrophic obstructive cardiomyopathy (HOCM) with symptomatic LVOT obstruction (gradient ≥50 mmHg at rest or with provocation) refractory to medical therapy. Technique: identify the first or second septal perforator branch supplying the basal septum; confirm territory with myocardial contrast echocardiography; inject 1-3 mL of absolute (96-100%) ethanol to create a controlled septal infarction. Result: septal thinning and regression of LVOT gradient over 3-6 months. Success rate: 85-95% gradient reduction.

Complications: complete heart block requiring PPM (10-20%), LAD dissection, coronary spasm, VSD (rare), and RV perforation. ASA is an alternative to surgical septal myectomy (gold standard), particularly in patients at high surgical risk, elderly patients, or those with comorbidities. The long-term scar from ASA may serve as a substrate for ventricular arrhythmias, though large registries have not shown excess sudden death.

ASA vs Septal Myectomy — Comparison

Paravalvular Leak (PVL) Closure

Paravalvular leaks occur around surgically implanted prosthetic valves, causing hemolysis (mechanical shear stress), heart failure (volume overload), or both. Transcatheter closure uses Amplatzer Vascular Plug (AVP II, AVP IV) or other occluder devices delivered via retrograde aortic (for aortic PVL) or transseptal (for mitral PVL) approach. Success rates: 75-90%. Complications include device embolization, valve impingement, and residual leak.

15 Peripheral Vascular Interventions

Carotid Artery Stenting (CAS) & TCAR

CAS is an alternative to carotid endarterectomy (CEA) for significant carotid stenosis. Indications: symptomatic carotid stenosis ≥50% or asymptomatic stenosis ≥70% with high surgical risk. Embolic protection devices (EPDs) — distal filter (FilterWire, SpiderFX) or proximal occlusion (Mo.Ma) — are mandatory during CAS to reduce stroke risk. TCAR (transcarotid artery revascularization) uses direct carotid access with flow reversal via an arteriovenous circuit, providing superior neuroprotection. The ROADSTER trials demonstrated 30-day stroke/death rates <2% with TCAR.

Renal Artery Interventions

Renal artery stenting for atherosclerotic renal artery stenosis was not shown to improve outcomes over medical therapy in the CORAL and ASTRAL trials. However, intervention may be considered for: flash pulmonary edema (Pickering syndrome), refractory hypertension on ≥3 medications, progressive renal deterioration with bilateral disease, and fibromuscular dysplasia (balloon angioplasty without stenting — good results). For FMD, the "string of beads" appearance on angiography is characteristic of the medial fibroplasia subtype.

Renal denervation (RDN): Catheter-based ablation of the renal sympathetic nerves for resistant hypertension. Radiofrequency (Symplicity Spyral) or ultrasound-based (Paradise) energy is delivered to the renal artery adventitia. The SPYRAL HTN-ON MED and RADIANCE-HTN SOLO trials showed modest but significant BP reductions (5-10 mmHg systolic) vs sham. RDN is approved in Europe and under FDA review. Patient selection is critical — best candidates are those with true resistant hypertension after confirming medication adherence.

Lower Extremity Peripheral Arterial Disease (PAD)

Endovascular revascularization is indicated for lifestyle-limiting claudication refractory to exercise therapy and pharmacotherapy, and for chronic limb-threatening ischemia (CLTI) with rest pain, ulceration, or gangrene. The Global Vascular Guidelines (GVG) use the WIfI classification (Wound, Ischemia, foot Infection) to stage CLTI severity and guide management.

Aortic Interventions

Thoracic Endovascular Aortic Repair (TEVAR): Endograft placement for descending thoracic aortic aneurysms (≥5.5 cm or rapid growth >0.5 cm/year) and complicated type B aortic dissections (malperfusion, rupture, refractory pain/hypertension). Landing zone classification (Ishimaru zones 0-4) determines feasibility and need for supra-aortic debranching. Zone 2 (distal to left common carotid) is the minimum proximal landing zone without left subclavian revascularization (though LSA coverage should be revascularized if possible — CSRA, left carotid-subclavian bypass).

Endovascular Aneurysm Repair (EVAR): For infrarenal abdominal aortic aneurysms (≥5.5 cm in men, ≥5.0 cm in women, or growth >0.5 cm/6 months). Anatomic requirements: infrarenal neck ≥10-15 mm, neck angle <60°, iliac diameter ≥7 mm for device delivery. Complications: endoleak (Type I — proximal/distal seal failure; Type II — branch vessel back-bleeding [most common]; Type III — graft fabric/junction failure; Type IV — graft porosity; Type V — endotension), limb occlusion, and post-implantation syndrome.

Pulmonary Embolism Interventions

Catheter-directed therapy (CDT) for massive and submassive PE includes: catheter-directed thrombolysis (CDT) — ultrasound-facilitated low-dose tPA delivery (EKOS/EkoSonic — ULTIMA, SEATTLE-II trials), aspiration thrombectomy (FlowTriever — FLARE trial; Indigo — EXTRACT-PE trial), and rheolytic thrombectomy. The FlowTriever device uses large-bore aspiration and self-expanding nitinol discs to mechanically remove thrombus without fibrinolytic agents, reducing bleeding risk. CDT for submassive PE (RV dysfunction without hemodynamic instability) remains an area of active investigation (HI-PEITHO trial).

16 Mechanical Circulatory Support

Intra-Aortic Balloon Pump (IABP)

The IABP is a counterpulsation device inserted via the femoral artery and positioned in the descending aorta just distal to the left subclavian artery. Inflation during diastole augments coronary perfusion pressure and diastolic blood pressure. Deflation during systole reduces afterload, LV wall stress, and myocardial oxygen demand. Timing: inflation at the dicrotic notch; deflation just before systole. The IABP-SHOCK II trial showed no mortality benefit of IABP in cardiogenic shock complicating MI, leading to a downgrade in guidelines. IABP remains useful as an adjunct for mechanical complications (acute MR, VSD) and as a bridge in selected patients.

Impella Devices

The PROTECT III trial demonstrated that Impella-supported high-risk PCI reduced major adverse events at 90 days compared to IABP support. Complications of Impella include: hemolysis (monitor plasma-free hemoglobin), limb ischemia, aortic valve injury, device migration, and ventricular perforation.

Venoarterial ECMO (VA-ECMO)

VA-ECMO provides full cardiopulmonary support by draining deoxygenated blood from the venous system (femoral vein or RA), passing it through an oxygenator and heat exchanger, and returning oxygenated blood to the arterial system (femoral artery or aorta). VA-ECMO can provide flows of 3-7 L/min independent of cardiac function. Emergency Indications include: refractory cardiogenic shock (SCAI D-E), cardiac arrest (ECPR — extracorporeal CPR), post-cardiotomy shock, massive pulmonary embolism, and bridge to transplant/LVAD decision.

Key consideration: VA-ECMO increases LV afterload (retrograde arterial flow) and may worsen LV distension, pulmonary edema, and LV thrombus formation. LV venting strategies — Impella, IABP, atrial septostomy, or direct LA/LV vent — are often required to unload the LV during VA-ECMO support.

TandemHeart

The TandemHeart is a percutaneous left atrial-to-femoral artery bypass system. A 21 Fr transseptal inflow cannula is placed in the LA; oxygenated blood is withdrawn and pumped to the femoral artery via an extracorporeal centrifugal pump, providing up to 5 L/min of flow. Advantages: effective LV unloading (bypasses the LV entirely). Disadvantages: requires transseptal puncture, large-bore venous and arterial access, residual ASD after decannulation, and risk of limb ischemia. Largely supplanted by Impella in current practice.

Device Selection by Shock Severity

SCAI Shock Classification

17 Advanced Hemodynamic Profiles & Waveforms

Hemodynamic Profiles in Shock

RA Waveform Analysis

The RA waveform consists of: a wave (atrial contraction), c wave (tricuspid closure/bulging), x descent (atrial relaxation/tricuspid annular descent), v wave (passive atrial filling against a closed tricuspid valve), and y descent (tricuspid opening and passive ventricular filling). Key abnormalities: Giant a waves — tricuspid stenosis, pulmonary hypertension, RV hypertrophy; Cannon a waves — AV dissociation, complete heart block, V-pacing without AV synchrony; Large v waves — severe TR; Absent a waves — atrial fibrillation; Prominent x descent — tamponade (exaggerated); Blunted y descent — tamponade; Steep y descent — constriction, severe TR.

PCWP Waveform

The PCWP tracing mirrors the LA pressure waveform with a phase delay of 50-100 ms. Key findings: Large v waves in the PCWP suggest severe mitral regurgitation (v wave amplitude ≥2x mean PCWP is highly suggestive). However, large v waves can also occur with increased LA compliance (chronic MR) or with VSD (left-to-right shunt increasing pulmonary venous return). The a wave in PCWP corresponds to LA contraction — absent in AF; giant a waves in mitral stenosis.

Provocative Maneuvers

Rapid volume loading (500-1000 mL saline): Used to unmask constrictive physiology — RVEDP and LVEDP will rise and equalize with characteristic dip-plateau pattern. Dynamic respiratory assessment: In constriction, RV and LV systolic pressures show discordance with respiration (RV pressure rises while LV pressure falls during inspiration) — this is the most sensitive and specific hemodynamic finding for constriction. In tamponade, RV and LV systolic pressures show concordance (both fall during inspiration). Exercise hemodynamics: Supine bicycle exercise in the cath lab unmasks heart failure with preserved ejection fraction (HFpEF) — a PCWP ≥25 mmHg with exercise is diagnostic.

PA Pulsatility Index (PAPi)

PAPi = (PA systolic - PA diastolic) / RA mean pressure. PAPi is a marker of RV function. A PAPi <0.9 predicts RV failure requiring RVAD support after LVAD implantation. In the setting of acute inferior MI, a PAPi <1.0 predicts hemodynamically significant RV infarction and the need for RV mechanical support. PAPi is increasingly used to assess RV reserve before MCS implantation and to guide the need for biventricular support (BiVAD or TAH) versus isolated LVAD.

Hemodynamic Assessment During Intervention

LVEDP measurement: Obtained by pigtail catheter in the LV; elevated LVEDP (>18 mmHg) correlates with HF and increased periprocedural risk. Used in the POSEIDON protocol for CIN prevention (hydration rate adjusted to LVEDP). Aortic regurgitation assessment: Aortography graded by Sellers classification (0-4+) based on density and washout of contrast from the LV. Simultaneous pressure measurement across the aortic valve (dual-lumen catheter or femoral artery + LV) provides peak-to-peak gradient and mean gradient for AS severity assessment.

18 Access Site Complications

Femoral Access Complications

Retroperitoneal hemorrhage: Emergency Occurs with high femoral arterial puncture (above the inguinal ligament) or through-and-through puncture. Presents with hemodynamic instability, back/flank pain, ipsilateral abdominal distension, and unexplained Hgb drop. Diagnosis: CT abdomen/pelvis with contrast. Management: volume resuscitation, reversal of anticoagulation, blood transfusion, and covered stent or surgical repair for active extravasation. Maintain a low threshold for diagnosis — mortality is 4-12%.

Pseudoaneurysm: Pulsatile mass at the access site with a "to-and-fro" signal on duplex ultrasound. Small (<2 cm) pseudoaneurysms may thrombose spontaneously. Treatment: ultrasound-guided thrombin injection (first-line — 95% success rate), ultrasound-guided compression, or surgical repair for large or failed cases.

Arteriovenous (AV) fistula: Communication between the femoral artery and vein, detected by continuous bruit/thrill and confirmed by duplex showing arterialized venous flow. Most small fistulae (<5 mm) close spontaneously. Large or symptomatic fistulae require covered stent placement or surgical repair.

Femoral artery dissection / occlusion: Can result from catheter manipulation, closure device deployment, or guide wire trauma. Presents with limb ischemia (acute pain, pallor, pulselessness). Management: angiography with stenting or surgical repair.

Radial Access Complications

Radial artery occlusion (RAO): Occurs in 1-10% of cases; usually asymptomatic due to dual palmar arch supply. Prevention: use smallest effective sheath, patent hemostasis (maintain antegrade flow during compression with pulse oximetry/plethysmography), and adequate anticoagulation (UFH ≥50 U/kg). Radial artery spasm: Prevented with intra-arterial verapamil/nitroglycerin cocktail and hydrophilic-coated sheaths. Managed with additional vasodilators and gentle catheter manipulation — never force catheter withdrawal against spasm (risk of avulsion).

Compartment syndrome: Rare but devastating complication from perforation of a small radial branch. Presents with forearm swelling, pain, and neurovascular compromise. Emergency Treatment: emergent fasciotomy.

Large-Bore Access Complications

TAVR, MCS, and ECMO require large-bore femoral access (14-24 Fr). Specific complications include:

Iliac rupture / dissection: Occurs during sheath insertion in calcified, tortuous, or small iliofemoral arteries. Presents with sudden hypotension and contrast extravasation on iliac angiography. Management: balloon tamponade followed by covered stent deployment (iCAST, Viabahn). Surgical repair if endovascular approach fails.

Acute limb ischemia: Large sheaths can obstruct distal flow, especially if sheath diameter exceeds the vessel lumen. Prevention: place a distal perfusion catheter (DPC) for VA-ECMO and prolonged large-bore access. Treatment: thrombectomy, fasciotomy if compartment syndrome develops.

Lymphocele / lymphatic injury: Disruption of inguinal lymphatics during access, presenting as a fluctuant non-pulsatile groin mass days to weeks after the procedure. Most resolve spontaneously; aspiration or sclerotherapy for large or symptomatic collections.

BARC Bleeding Classification

19 Procedural Complications

Contrast-Induced Nephropathy (CIN)

CIN is defined as a rise in serum creatinine of ≥0.5 mg/dL or ≥25% from baseline within 48-72 hours of contrast exposure. Risk factors: pre-existing CKD (eGFR <60), diabetes, volume depletion, contrast volume, hemodynamic instability, and nephrotoxic agents. Prevention: adequate hydration (IV NS 1 mL/kg/h for 3-12 h pre- and 6-12 h post-procedure — POSEIDON protocol targets LVEDP-guided hydration), minimize contrast volume (target contrast/eGFR ratio <3.7), use iso-osmolar or low-osmolar contrast, avoid nephrotoxic agents (NSAIDs, aminoglycosides), and hold metformin for 48 hours post-contrast. N-acetylcysteine has not shown consistent benefit (PRESERVE trial — no benefit of NAC or IV sodium bicarbonate over IV saline).

Coronary Perforation

See Section 10 for Ellis classification and management. Additional considerations: Wire perforation (most common cause) — typically Type I-II; managed by balloon inflation proximal to the perforation, reversal of anticoagulation with protamine, and observation. Balloon/stent perforation — oversized balloon or stent in a diseased vessel; managed with covered stent (PK Papyrus). Atherectomy perforation — rotational or orbital atherectomy in a tortuous or thin-walled segment; high risk of Type III perforation.

Stroke During Cardiac Catheterization

Periprocedural stroke occurs in 0.1-0.4% of diagnostic catheterizations and 0.2-0.6% of PCI. Risk factors: aortic arch atheroma, prolonged procedure, catheter manipulation in the aortic root, atrial fibrillation, and left heart catheterization via femoral approach. Management: immediate neurology consultation, CT head to exclude hemorrhagic stroke, catheter-directed thrombectomy or IV tPA if within the appropriate time window, and supportive care.

Air Embolism

Coronary air embolism presents with acute ST elevation, hemodynamic collapse, and chest pain. Emergency Management: vigorous aspiration through the guide catheter, forceful injection of saline and blood (to fragment air bubbles), 100% oxygen (accelerates nitrogen reabsorption), and intracoronary vasodilators for associated spasm. Prevention: meticulous catheter aspiration and flushing, avoiding back-bleeding of guide catheters, and careful attention to manifold connections. Large-volume air embolism (manifold disconnection or sheath flushing error) can cause immediate cardiovascular collapse requiring CPR and potentially emergent percutaneous aspiration from the coronary arteries or aortic root.

Coronary Spasm (Iatrogenic)

Catheter-induced spasm occurs at the site of guide catheter engagement or wire manipulation. More common with radial access (spasm of the radial artery itself is distinct from coronary spasm). Treatment: intracoronary nitroglycerin (100-200 μg bolus, may repeat), intracoronary verapamil (100-200 μg if NTG ineffective), or intracoronary nicardipine (100-200 μg). Refractory spasm may mimic acute occlusion — always consider spasm before escalating to emergent intervention. Patients with known variant (Prinzmetal) angina may have heightened vasoreactivity; pretreat with IC NTG before diagnostic injection.

Radiation Skin Injury

Prolonged fluoroscopy during complex PCI (CTO, chronic total occlusions) can cause radiation dermatitis. Effects are dose-dependent: 2-5 Gy — transient erythema; 5-10 Gy — prolonged erythema, dry desquamation; 10-15 Gy — moist desquamation, pain; >15 Gy — dermal necrosis, ulceration. The patient's back is the most commonly affected site (entrance skin dose). Monitoring: real-time air kerma display; alert at 5 Gy (sentinel event). Management: dermatology referral for skin injuries >5 Gy; wound care for ulceration. Prevention: limit fluoroscopy time, use low-dose protocols, change angulation to distribute dose across skin surface.

Catheter-Induced Coronary Dissection

Occurs during guide catheter engagement or aggressive manipulation, particularly with Amplatz-type catheters in the RCA. The NHLBI dissection classification grades severity:

Left main dissection is a catastrophic complication requiring immediate stenting to restore flow. If left main dissection extends to the aortic root, emergent surgical consultation is required.

Cholesterol Embolization Syndrome

Shower of cholesterol crystals from disrupted aortic atherosclerotic plaques during catheter manipulation. Presents days to weeks after the procedure with: blue/purple toes (livedo reticularis) with palpable pedal pulses, renal failure (progressive, may require dialysis), eosinophilia, elevated ESR, low complement, and Hollenhorst plaques on fundoscopy. Diagnosis is clinical; skin or renal biopsy shows biconvex "cleft" spaces (cholesterol crystals dissolved during processing). There is no specific treatment — supportive care, statin therapy, and avoidance of further catheterization if possible. Mortality rate is 70-90% when systemic involvement is severe.

20 Antithrombotic Protocols & Bleeding Management

DAPT Protocols by Indication

Triple Therapy — AF + PCI

Patients with AF requiring OAC who undergo PCI face competing risks of thromboembolism (stent thrombosis, stroke) and bleeding (triple therapy). Current evidence favors minimizing triple therapy duration:

WOEST — Dual therapy (OAC + clopidogrel, no aspirin) reduced bleeding without increasing ischemic events. RE-DUAL PCI — Dabigatran + P2Y12 inhibitor vs triple therapy: non-inferior for ischemic events, lower bleeding. AUGUSTUS — Apixaban + P2Y12 inhibitor (without aspirin) was the safest strategy; aspirin should be dropped by 1-4 weeks. ENTRUST-AF PCI — Edoxaban + P2Y12 inhibitor was non-inferior to triple therapy.

Current approach: Triple therapy (OAC + DAPT) for 1 week to 1 month maximum → dual therapy (DOAC + P2Y12 inhibitor, drop aspirin) for up to 12 months → OAC monotherapy lifelong. Use a DOAC (not warfarin) and clopidogrel (not prasugrel or ticagrelor) to minimize bleeding.

Special Considerations — Mechanical Heart Valves

Patients with mechanical prosthetic valves requiring PCI present a unique challenge — warfarin (not DOACs) is mandatory for valve thrombosis prevention. The INR target is 2.5-3.5 for mechanical mitral valves and 2.0-3.0 for mechanical aortic valves. After PCI: triple therapy (warfarin + ASA + clopidogrel) for 1 month → warfarin + single antiplatelet for 12 months → warfarin alone. Radial access and BMS (to shorten DAPT) or second-gen DES with shortened DAPT should be considered. DOACs are contraindicated with mechanical valves (RE-ALIGN trial — dabigatran caused thromboembolic and bleeding complications).

CKD & Dialysis Patients

Patients with CKD (eGFR <30) and dialysis patients have higher rates of bleeding, stent thrombosis, and mortality after PCI. Key considerations: minimize contrast volume (consider IVUS-guided "zero-contrast" PCI for severe CKD); iso-osmolar contrast (iodixanol) may reduce CIN risk; BMS vs DES decision is individualized (DES preferred if life expectancy >1 year); prasugrel and ticagrelor lack strong safety data in dialysis — clopidogrel is generally preferred; bivalirudin may be preferred over UFH (predictable pharmacokinetics); fondaparinux is contraindicated if CrCl <30. Dialysis timing: schedule dialysis 24-48 hours post-procedure if contrast was used.

Perioperative Bridging of DAPT

Elective non-cardiac surgery should ideally be deferred for 6 months after DES implantation (minimum 3 months with newer-gen DES) and 1 month after BMS. If surgery cannot be delayed, aspirin should be continued perioperatively in most cases. P2Y12 inhibitors should be held for 5 days (clopidogrel, ticagrelor) or 7 days (prasugrel) before surgery. Bridging with cangrelor or GP IIb/IIIa inhibitors is reserved for very high-risk patients (recent stent <30 days) who require urgent surgery. There is no evidence supporting routine bridging with IV heparin for DAPT cessation.

Timing of Surgery After Stent Implantation

Bleeding Management & Reversal Agents

21 Classification Systems

SYNTAX Score

Angiographic scoring system for coronary disease complexity. Low (≤22): PCI equivalent to CABG; Intermediate (23-32): Heart Team discussion; High (≥33): CABG preferred. Variables: number of lesions, segments involved, total occlusions, trifurcation/bifurcation, aorto-ostial lesions, severe tortuosity, calcification, thrombus, vessel length >20 mm, small vessels, and diffuse disease.

TIMI Risk Score — STEMI

Predicts 30-day mortality in STEMI (0-14 points): Age (65-74 = 2, ≥75 = 3), diabetes/HTN/angina (1), SBP <100 (3), HR >100 (2), Killip II-IV (2), weight <67 kg (1), anterior STEMI or LBBB (1), time to treatment >4 h (1).

TIMI Risk Score — UA/NSTEMI

Predicts 14-day risk of death, MI, or urgent revascularization (0-7 points, 1 each): Age ≥65, ≥3 CAD risk factors, known CAD (≥50% stenosis), ASA use in past 7 days, ≥2 anginal events in 24 h, ST deviation ≥0.5 mm, elevated cardiac biomarkers.

GRACE Score

Most validated risk score for in-hospital and 6-month mortality in ACS. Variables: age, heart rate, SBP, creatinine, Killip class, cardiac arrest, ST deviation, elevated biomarkers. Low risk (<109): <1% mortality; Intermediate (109-140): 1-3%; High (>140): >3% — early invasive strategy recommended.

CRUSADE Bleeding Score

Predicts in-hospital major bleeding risk in NSTEMI patients. Variables (0-100 points): baseline hematocrit, creatinine clearance, heart rate, SBP, sex, diabetes, prior vascular disease, and signs of CHF. Very low (≤20): 3% bleed risk; Low (21-30): 6%; Moderate (31-40): 9%; High (41-50): 12%; Very high (>50): 19%. Helps guide selection of antithrombotic intensity and vascular access strategy.

HEART Score

Used for chest pain risk stratification in the emergency department (0-10 points): History (0-2), ECG (0-2), Age (0-2), Risk factors (0-2), Troponin (0-2). Score 0-3: low risk (safe for discharge); 4-6: moderate risk (observation, further testing); 7-10: high risk (early invasive strategy). Validated in the HEART Pathway trial for safe early discharge of low-risk chest pain patients.

CCS Angina Classification

Killip Classification — Acute MI

NYHA Functional Classification

ARC Stent Thrombosis Classification

Definite: Angiographic or pathological confirmation of thrombus within the stent. Probable: Unexplained death within 30 days of stent implantation, or any MI in the stented territory without angiographic confirmation. Possible: Unexplained death >30 days after stent implantation. Timing: Acute (0-24 h), subacute (1-30 d), late (30 d-1 y), very late (>1 y).

Ellis Coronary Perforation Classification

See Section 10 for full details. Type I: extraluminal crater; Type II: myocardial/pericardial blush; Type III: frank perforation with streaming; Cavity spilling: into cardiac chamber.

Mehran In-Stent Restenosis Classification

Type I: focal (≤10 mm); Type II: diffuse intra-stent (>10 mm); Type III: proliferative (extending beyond stent margins); Type IV: total occlusion.

Medina Bifurcation Classification

Three-digit code describing involvement (1 = ≥50% stenosis, 0 = <50%) of the proximal main branch, distal main branch, and side branch: 1,1,1 = all three segments; 1,1,0 = main vessel only; 0,0,1 = side branch only; 1,0,1 = proximal main and side branch (Medina classification is essential for bifurcation PCI planning).

Rentrop Collateral Classification

Grade 0: No filling of collateral channels. Grade 1: Filling of side branches of the occluded vessel via collateral channels, without visualization of the epicardial segment. Grade 2: Partial filling of the epicardial artery via collateral channels. Grade 3: Complete filling of the epicardial artery by collateral channels.

Wilkins Score (Mitral Balloon Valvuloplasty)

Each parameter scored 1-4 (total 4-16): Leaflet mobility (1 = mobile, 4 = immobile); Leaflet thickening (1 = near-normal, 4 = severe); Subvalvular thickening (1 = minimal, 4 = extensive); Calcification (1 = none, 4 = extensive). Score ≤8: favorable for PBMV; >8: consider surgical MVR.

RoPE Score (PFO-Associated Stroke)

Risk of Paradoxical Embolism score (0-10 points): age (0-5 points based on age 18-≥70), no hypertension (1), no diabetes (1), no stroke/TIA (1), nonsmoker (1), cortical infarct on imaging (1). Higher score = greater probability that PFO is causally related to the stroke (and greater benefit from closure). RoPE ≥7: ~84% probability PFO is pathogenic.

J-CTO Score (CTO Difficulty)

Predicts guidewire crossing within 30 minutes (0-5 points, 1 each): Blunt proximal cap, Calcification, Bending >45°, Occlusion length >20 mm, Prior failed attempt. Score 0: easy (success ~90%); 1: intermediate (~75%); 2: difficult (~55%); ≥3: very difficult (<40% wire crossing in 30 min).

PROGRESS-CTO Score

Predicts technical success of CTO PCI using the hybrid algorithm (0-6 points): proximal cap ambiguity (1), absence of interventional collateral (1), moderate-severe tortuosity (1), circumferential calcification (1), CTO length ≥20 mm (1), prior failed attempt (1). Score 0-1: >90% success; 2: ~85%; 3: ~75%; ≥4: <65% success. Unlike the J-CTO score, PROGRESS-CTO accounts for collateral quality, which is essential for retrograde strategy selection.

Sellers Classification (Aortic Regurgitation on Aortography)

WIfI Classification (Chronic Limb-Threatening Ischemia)

The Wound, Ischemia, and foot Infection (WIfI) classification stages CLTI severity on a 0-3 scale for each domain: Wound (0 = no ulcer, 3 = extensive gangrene); Ischemia (0 = ABI ≥0.80, 3 = ABI ≤0.39 or absolute toe pressure <30 mmHg); foot Infection (0 = none, 3 = SIRS/sepsis). Combined staging predicts amputation risk and benefit from revascularization. WIfI stages 3-4 (high ischemia, high wound burden) benefit most from revascularization.

DAPT Score

Predicts benefit vs risk of prolonged DAPT after PCI (range -2 to 10): Positive score (≥2) — benefit from extended DAPT (ischemic risk reduction outweighs bleeding risk). Negative score (<2) — bleeding risk outweighs ischemic benefit; favor shorter DAPT. Variables: age (≥75 = -2, 65-74 = -1), smoking (+1), diabetes (+1), MI at presentation (+1), prior PCI or MI (+1), paclitaxel stent (+1), stent diameter <3 mm (+1), CHF/LVEF <30% (+2), vein graft PCI (+2).

22 Medications Master Table

Antiplatelet Agents

Anticoagulants

GP IIb/IIIa Inhibitors

Vasodilators & Vasopressors

23 Imaging & Diagnostics Reference

Coronary Angiography Views — Quick Reference

IVUS vs OCT Comparison

FFR / iFR Decision Matrix

Coronary CTA (CCTA)

Coronary CT angiography is a non-invasive alternative to invasive angiography for evaluating coronary anatomy and stenosis. Key metrics: CT-FFR (FFRCT) — computational fluid dynamics applied to CCTA images to estimate FFR non-invasively (PLATFORM, ADVANCE trials); Stenosis severity — <50% (non-obstructive), 50-69% (moderate), ≥70% (severe), ≥50% left main; High-risk plaque features — positive remodeling, low-attenuation plaque (<30 HU), napkin-ring sign, spotty calcification. CCTA is endorsed as a first-line test for chest pain evaluation in low-intermediate risk patients (NICE guidelines, PROMISE, SCOT-HEART trials).

CT Coronary Calcium Scoring (Agatston Score)

Echocardiography for Structural Procedures

TEE for TAVR: Confirms annular sizing, guides valve positioning, assesses paravalvular leak, detects pericardial effusion, and evaluates LV function. TEE for TEER: Guides transseptal puncture, visualizes leaflet grasping, assesses residual MR, and monitors for complications (pericardial effusion, single-leaflet device attachment). ICE (intracardiac echo): Increasingly used for ASD/PFO closure, LAA closure, and transseptal puncture guidance — eliminates need for general anesthesia required with TEE.

Transseptal Puncture — Technical Considerations

Transseptal access is the gateway to all left-sided structural interventions (TEER, LAAC, TMVR, PBMV, PFO/ASD closure). The ideal puncture site varies by procedure: TEER — posterior and superior (4-4.5 cm above the mitral annulus); LAAC — posterior and inferior (directed toward the LAA ostium); PBMV — posterior and inferior. Equipment: Brockenbrough needle (BRK or BRK-1), Mullins sheath or deflectable sheath (Agilis). Puncture site is confirmed by tenting of the fossa ovalis on TEE or ICE. Complications: cardiac perforation/tamponade (0.5-1%), aortic root puncture, air embolism, and residual ASD (usually closes spontaneously; rarely hemodynamically significant).

24 Abbreviations Master List

25 Landmark Trials

Coronary Revascularization Strategy

Coronary Physiology & Imaging

STEMI & ACS

Antiplatelet Therapy

Structural Heart

Mechanical Circulatory Support

Bifurcation & CTO Trials

Triple Therapy Trials