Who benefits from Coronary Artery Bypass Grafting (CABG) in Acute Coronary Syndrome (ACS)?

Who Benefits from CABG in Acute Coronary Syndrome

In patients with ACS and multivessel disease, CABG provides superior survival compared to PCI or medical management alone, particularly in those with diabetes, left main disease, complex three-vessel disease (SYNTAX score >22), or left ventricular dysfunction (LVEF <50%). 1, 2, 3

Specific Patient Populations Who Benefit Most

Multivessel Disease with Diabetes Mellitus

• CABG is mandatory over both PCI and medical therapy in diabetic patients with multivessel disease involving the left anterior descending artery. 1, 2
• The FREEDOM trial demonstrated significant survival advantages with CABG versus PCI in this population, with lower rates of death and myocardial infarction. 4
• This benefit is amplified when a left internal mammary artery (LIMA) graft can be anastomosed to the LAD artery. 1, 2
• At 1-year follow-up in ACS patients with diabetes and multivessel disease, CABG shows comparable mortality to PCI but significantly lower repeat revascularization rates (5.2% vs 19.5%). 5

Complex Three-Vessel Disease

• CABG is the definitive treatment for patients with complex three-vessel disease (SYNTAX score >22), providing Class I, Level A evidence for improved survival, reduced MI, and lower revascularization rates compared to PCI. 1, 2, 6
• The survival benefit is even greater when LVEF is less than 50%. 7
• High complexity three-vessel disease treated with CABG shows mortality rates of 2.9% versus 6.2% with PCI at 3 years. 2
• In contemporary real-world data from 2018-2022, patients with ACS and multivessel disease treated with CABG had significantly lower 1-year mortality (5.1%) compared to PCI (14.1%) or medical management (13.4%). 3

Left Main Disease

• CABG is recommended as Class I therapy for all patients with significant left main stenosis (≥50%) to improve survival, and is the overall preferred revascularization mode over PCI. 1, 2
• High complexity left main disease shows a 31.4% MACE rate with PCI versus significantly lower rates with CABG at 3 years. 2
• The only exception is left main disease of low complexity (SYNTAX score ≤22) where PCI can provide equivalent completeness of revascularization; in this scenario, PCI is an acceptable alternative given its lower invasiveness. 1

Left Ventricular Systolic Dysfunction

• CABG improves long-term survival in patients with LVEF ≤35% and multivessel disease, with Class I, Level B recommendation. 1, 2
• Even in patients with mild-to-moderate LV dysfunction (LVEF 35-50%) and significant multivessel disease or proximal LAD stenosis, CABG is reasonable when viable myocardium is present. 1

Proximal LAD Involvement

• CABG with LIMA graft to the LAD is reasonable in patients with significant proximal LAD stenosis and evidence of extensive ischemia. 1
• In complex single- or double-vessel disease involving the proximal LAD that is less amenable to PCI, CABG is recommended to improve symptoms and reduce revascularization rates. 1

Critical Timing Considerations in ACS

When to Perform CABG

• In STEMI with multivessel disease, complete revascularization with staged PCI of non-infarct arteries (up to 45 days post-MI) is preferred over immediate multivessel PCI, but patients with complex disease suited for CABG should be identified early. 1
• Early CABG during index ACS hospitalization, despite being performed in higher-risk patients, is associated with very low in-hospital mortality (1.1%) compared to PCI (2.2%) or medical management (6.8%). 8
• Staged CABG after culprit-vessel PCI for STEMI is a feasible option in selected patients with complex non-infarct-related artery disease. 9

When NOT to Perform CABG

• In STEMI complicated by cardiogenic shock with multivessel disease, culprit vessel-only PCI is superior to multivessel PCI; CABG timing in this setting requires careful consideration of bleeding risk from dual antiplatelet therapy. 1
• Avoid CABG within 3-7 days of acute MI unless there is ongoing ischemia with hemodynamic compromise, as surgical mortality is elevated during this window. 7

Anatomic Complexity Assessment

SYNTAX Score Utilization

• Calculate the SYNTAX score in all patients with multivessel disease to assess anatomical complexity (Class I, Level B recommendation). 1
• SYNTAX score >22 mandates CABG over PCI. 2, 6
• SYNTAX score ≤22 allows consideration of PCI as an alternative if complete revascularization can be achieved. 1

Heart Team Approach

• A Heart Team discussion is mandatory for all patients with unprotected left main or complex coronary disease to determine optimal revascularization strategy based on coronary anatomy, LVEF, diabetes status, and surgical risk. 1, 2, 6

Common Pitfalls to Avoid

• Do not extrapolate the benefits of multivessel PCI in STEMI trials to patients with complex disease (left main, chronic total occlusions, high SYNTAX scores), as these patients were excluded from those trials. 1
• Do not defer CABG in asymptomatic or mildly symptomatic patients with three-vessel disease, as the survival benefit exists regardless of symptom severity. 7
• Do not withhold CABG in elderly patients based on age alone when surgical risk is acceptable. 7
• Ensure clopidogrel is discontinued at least 5 days before surgery and ticagrelor/prasugrel at least 7 days before to limit bleeding and transfusions. 1
• Do not perform PCI in patients with high SYNTAX scores (≥33) and three-vessel disease, as this is contraindicated (Class III recommendation). 7