How do you manage chronic total occlusions (CTO)?

Management of Chronic Total Occlusions (CTO)

The primary indication for CTO intervention is symptom improvement in patients with refractory angina or angina-equivalent symptoms (dyspnea, exercise limitation, fatigue) despite optimal medical therapy, particularly when documented ischemia ≥10% of the left ventricle is present in viable myocardium. 1, 2

Initial Assessment and Patient Selection

When to Intervene

• Pursue CTO-PCI when patients have persistent symptoms despite optimal medical therapy AND documented ischemia ≥10% of the myocardium with demonstrated viability in the CTO territory 1, 2
• The ACC/AHA provides a Class IIa, Level B recommendation for CTO-PCI in patients with appropriate clinical indications and suitable anatomy when performed by expert operators 1, 2
• Patients frequently present with atypical symptoms including shortness of breath, exercise limitation, and fatigue rather than classic angina 2

When NOT to Intervene

• Avoid CTO-PCI in asymptomatic patients with low ischemic burden (<6.25%), as the risk of worsening ischemia outweighs potential benefit 2
• Do not attempt CTO-PCI without documented viability in dysfunctional territories, as absence of viability predicts poor functional recovery 2
• Defer intervention in patients with LVEF <30%, recent CVA (<8 weeks), or advanced malignancy during non-emergent procedures 3

Pre-Procedural Planning

Critical Planning Steps

• Never perform ad hoc CTO-PCI - schedule electively to allow adequate planning, patient counseling, and optimization of contrast/radiation dose 1, 2
• Perform dual coronary angiography to visualize CTO anatomy and collateral circulation 1, 2
• Review coronary CT angiography when available to assess occlusion length, calcification, and vessel course 2
• Conduct detailed angiographic review focusing on: (1) proximal cap morphology, (2) occlusion length/course/composition, (3) distal vessel quality, and (4) collateral characteristics 1

Risk Stratification

• Age, acute MI history, previous CABG, and ACEF score independently predict selection for medical therapy alone 4
• Multivessel disease, left main involvement, and high SYNTAX score favor CABG over PCI 4

Technical Approach to CTO-PCI

Essential Technical Principles

• Use dual coronary angiography with two catheters and pressure-monitoring systems in every case for better visualization, safety monitoring, and complication management 1
• Employ a microcatheter for essential guidewire support and manipulation 1
• Utilize intravascular imaging frequently to optimize stent deployment and minimize short- and long-term adverse events 1

Four Crossing Strategies

The following complementary strategies should be available 1:

1. Antegrade wire escalation (most common initial technique)
2. Antegrade dissection/reentry
3. Retrograde wire escalation
4. Retrograde dissection/reentry

Strategy Flexibility

• Change strategies promptly if initial approach fails to achieve progress - only 50-60% of CTOs are successfully crossed with the initial strategy 1
• Avoid "failure mode" where excessive time, radiation, and contrast are expended repeatedly attempting the same technique 1
• Small changes (modifying guidewire tip angulation) or significant changes (converting antegrade to retrograde approach) should be made based on preprocedural planning 1

When to Stop

Terminate the procedure if 1:

• Complication occurs
• High radiation dose (>5 Gy air kerma without substantial progress)
• Large contrast volume (>3.7× estimated creatinine clearance)
• Exhaustion of crossing options
• Patient or physician fatigue

Operator and Center Requirements

Expertise Requirements

• CTO-PCI should only be performed by operators with appropriate expertise at centers with dedicated CTO programs 1, 2
• Higher CTO-PCI volume consistently correlates with higher success rates (approximately 90% at experienced centers) 1, 5
• Centers must have specialized equipment, expertise, and experience to optimize success and minimize complications 1

Complication Management Preparedness

• Average complication risk is approximately 3%, with tamponade occurring in 0.4-1.3% of cases 1
• Have covered stents and coils immediately available for large vessel and distal vessel perforations, respectively 1
• For epicardial collateral perforation, embolization from both directions (coils, thrombin, fat) is often needed 1
• Special attention required for patients with previous CABG due to risk of life-threatening loculated hematomas or mediastinal/pleural bleeding 1

Clinical Outcomes Evidence

Benefits of Revascularization

• Symptom improvement and quality of life enhancement are consistently demonstrated in randomized trials for symptomatic patients 1, 2
• Reduction in ischemic burden is significant when baseline ischemia ≥12.5% 2
• Both CTO-PCI and CABG are independently associated with reduced all-cause mortality (HR 0.42 for PCI, HR 0.39 for CABG) and cardiac mortality compared to medical therapy alone 4

Limitations of Current Evidence

• Hard outcome benefits (mortality reduction) remain unproven in randomized trials and require confirmation in ongoing trials (ISCHEMIA-CTO, NOBLE-CTO) 1
• Observational studies suggesting mortality benefits are subject to bias 1
• No randomized studies demonstrate that CTO-PCI reduces ventricular arrhythmia risk, despite observational associations 1

Critical Pitfalls to Avoid

• Do not confuse acute thrombotic occlusion with CTO - acute occlusions require immediate intervention while CTOs require staged elective procedures 3
• Do not assume CABG guarantees better outcomes - approximately one-third of CTOs referred for CABG are not surgically revascularized, and graft occlusion rates are high in non-LAD territories 2
• Do not persist with inadequate guide catheter support - early recognition and catheter exchange prevent prolonged procedure time and complications 6
• Do not use forceful engagement techniques - gentle technique with appropriate catheter shape selection reduces dissection risk 6