What are the indications for Coronary Artery Bypass Grafting (CABG) versus Percutaneous Coronary Intervention (PCI)?

CABG vs PCI: Indications for Coronary Artery Bypass Grafting

CABG is the preferred revascularization strategy over PCI for patients with complex three-vessel disease (SYNTAX score >22), multivessel disease with diabetes, left main disease with high anatomical complexity, and significant proximal LAD stenosis with extensive ischemia, as these patients experience superior long-term survival and reduced rates of myocardial infarction and repeat revascularization. 1, 2

Anatomical Complexity-Based Decision Algorithm

Left Main Coronary Artery Disease

• CABG is recommended for left main disease at low surgical risk to improve survival and reduce spontaneous myocardial infarction and repeat revascularization compared to medical therapy alone 1
• CABG is the overall preferred mode over PCI for left main disease given lower risk of spontaneous MI and repeat revascularization 1
• PCI is an acceptable alternative only when left main disease has low complexity (SYNTAX score ≤22) and PCI can provide equivalent completeness of revascularization, offering non-inferior survival with lower invasiveness 1, 2
• PCI should be considered for intermediate complexity left main disease (SYNTAX score 23-32) when equivalent revascularization completeness is achievable 1
• CABG is strongly preferred for high SYNTAX score (≥33) left main disease 2

Three-Vessel Disease

• CABG is recommended over medical therapy alone for three-vessel disease with or without proximal LAD involvement to improve survival 1
• CABG should be chosen over PCI when complex three-vessel CAD is present (SYNTAX score >22) in good surgical candidates to improve survival 1
• PCI is acceptable for three-vessel disease with low-to-intermediate anatomical complexity (SYNTAX score ≤33) when PCI can provide similar completeness of revascularization, given lower invasiveness and generally non-inferior survival 1
• At 5-year follow-up, CABG resulted in significantly lower rates of major adverse cardiac and cerebrovascular events (24.2% vs 37.5%), death (9.2% vs 14.6%), MI (4.0% vs 9.2%), and repeat revascularization (12.6% vs 25.4%) compared to PCI in three-vessel disease 3

Two-Vessel Disease with Proximal LAD Involvement

• CABG is recommended for two-vessel disease involving proximal LAD to improve survival 1
• Both CABG and PCI are recommended over medical therapy alone for single- or double-vessel disease involving proximal LAD with insufficient response to guideline-directed medical therapy 1
• CABG is specifically recommended for complex proximal LAD lesions less amenable to PCI to improve symptoms and reduce revascularization rates 1, 4

Two-Vessel Disease without Proximal LAD

• CABG is reasonable when extensive ischemia is present 1
• The benefit of CABG is uncertain without extensive ischemia 1
• PCI benefit for survival is uncertain in this anatomical subset 1

Single-Vessel Proximal LAD Disease

• CABG with left internal mammary artery (LIMA) graft is reasonable for long-term benefit, particularly with extensive ischemia 1, 4
• PCI benefit for survival improvement is uncertain 1

Clinical Characteristics That Favor CABG

Diabetes Mellitus

• CABG is strongly recommended over PCI in patients with multivessel disease and diabetes to improve survival, particularly when LIMA can be anastomosed to the LAD 1, 2
• CABG in diabetics with multivessel disease resulted in 5-year MACCE of 18.7% compared to 26.6% with PCI 5
• The survival benefit and reduction in cardiac events with CABG is present regardless of coronary anatomy complexity in diabetic patients 5

Left Ventricular Dysfunction

• CABG is reasonable for patients with mild-moderate LV systolic dysfunction (ejection fraction 35-50%) and significant multivessel CAD or proximal LAD stenosis when viable myocardium is present 1, 2
• CABG might be considered for severe LV systolic dysfunction (EF <35%) whether or not viable myocardium is present, though evidence is less certain 1
• PCI should be considered for LV dysfunction patients at high surgical risk 1, 2

Survivors of Sudden Cardiac Death

• Both CABG and PCI are beneficial for survivors of sudden cardiac death with presumed ischemia-mediated ventricular tachycardia caused by significant stenosis in a major coronary artery 1

Risk Assessment Tools for Decision-Making

Heart Team Approach

• A Heart Team approach is recommended for all patients with unprotected left main or complex CAD 1, 2
• The Heart Team should include both interventional cardiologist and cardiac surgeon to discuss revascularization options with the patient 1

SYNTAX Score Calculation

• Calculation of SYNTAX score is recommended as it predicts adverse outcomes and guides revascularization decisions 1, 2
• SYNTAX score ≤22 indicates low complexity where PCI outcomes approach CABG 1, 3
• SYNTAX score 23-32 indicates intermediate complexity 1
• SYNTAX score >22 or ≥33 indicates high complexity where CABG demonstrates clear superiority 1, 2, 3

STS Score Calculation

• STS score calculation is recommended to predict surgical risk 1
• STS-predicted operative mortality ≥5% suggests significantly increased surgical risk favoring PCI consideration 1
• STS-predicted operative mortality ≥2% suggests increased surgical risk 1

Symptom Relief Indications

Unacceptable Angina Despite Medical Therapy

• Both CABG and PCI are beneficial for patients with one or more significant stenoses (>70% diameter) amenable to revascularization and unacceptable angina despite guideline-directed medical therapy 1
• CABG is reasonable to choose over PCI for symptom improvement in complex three-vessel CAD (SYNTAX score >22) in good surgical candidates 1

Previous CABG with Recurrent Symptoms

• PCI is reasonable for patients with previous CABG, significant stenoses associated with ischemia, and unacceptable angina despite medical therapy 1
• Repeat CABG might be reasonable when stenoses are not amenable to PCI 1

Contraindications to Revascularization

Anatomic and Physiologic Criteria

• CABG or PCI should not be performed in patients who do not meet anatomic criteria (>50% left main or >70% non-left main stenosis) or physiological criteria (abnormal fractional flow reserve) 1

PCI-Specific Contraindications

• PCI with stenting should not be performed if the patient cannot tolerate or comply with dual antiplatelet therapy for the appropriate duration 1

Common Pitfalls and Caveats

Stroke Risk Differential

• Stroke rates are significantly higher with CABG compared to PCI (2.2% vs 0.6% at 12 months) 6
• However, at 5-year follow-up in three-vessel disease, stroke rates were similar between CABG and PCI (3.5% vs 3.0%) 3

Repeat Revascularization Rates

• PCI consistently results in higher rates of repeat revascularization across all anatomical subsets 6, 3
• Even in low SYNTAX score patients where PCI is acceptable, repeat revascularization remains significantly higher (25.4% vs 12.6% at 5 years) 3

Diabetes Interaction

• The benefit of CABG over PCI is amplified in diabetic patients, with hazard ratio of 2.30 for diabetics versus 1.51 for non-diabetics 3

Incomplete Revascularization

• Complete revascularization generally provides better long-term outcomes than incomplete revascularization 7
• CABG results in more complete revascularization than PCI for complex lesions like left main and multivessel disease 8