What is the strategy for coronary artery bypass grafting (CABG) in patients with low ejection fraction (EF)?

CABG Strategy in Low Ejection Fraction Patients

CABG is reasonable and beneficial in patients with low ejection fraction (EF 35-50%) when significant multivessel disease or proximal LAD stenosis is present and viable myocardium exists in the region of intended revascularization, with even greater survival benefit when EF is below 50%. 1

Patient Selection Criteria

The key to successful outcomes is careful patient selection based on viability and anatomy:

• CABG should be performed in patients with EF <50% who have 3-vessel disease, as survival benefit is greater in this population compared to those with preserved EF 1
• For patients with severe LV systolic dysfunction (EF <35%), CABG might be considered with the primary intent of improving survival, whether or not viable myocardium is present 1
• Complete revascularization is essential—surgical treatment should only be undertaken when target coronary arteries are of relatively good diameter to achieve complete revascularization 2
• The presence of viable myocardium in the region of intended revascularization strengthens the Class IIa recommendation for patients with EF 35-50% 1

Preoperative Optimization

Hemodynamically unstable patients require mechanical circulatory support before surgery:

• Preoperative optimization with mechanical circulatory support devices, especially in the setting of hemodynamic instability, can reduce perioperative morbidity and mortality 3
• Patients with low EF have higher incidence of preoperative comorbidities including previous myocardial infarction, congestive heart failure, diabetes mellitus, and arterial hypertension—all independent predictors of in-hospital complications 2

Surgical Technique Considerations

Use the LIMA to LAD regardless of EF status:

• The left internal mammary artery (LIMA) should be used to bypass the left anterior descending artery in every patient, as this is associated with improved long-term outcomes even in low EF patients 1, 4
• The advantage of bilateral internal thoracic artery (BITA) grafting versus single internal thoracic artery (SITA) grafting in low EF patients remains unclear, with no demonstrated clinical benefit for BITA in individuals with EF <30% 5
• Off-pump CABG may offer reduced operative mortality (4.4% vs 5.4%) in low EF patients, though the advantage of this advanced technique remains unclear 3, 6

Expected Outcomes

Patients with low EF have acceptable but elevated perioperative risk:

• Operative mortality for on-pump CABG in patients with severe LV dysfunction (EF ≤35%) is approximately 5.4%, with 5-year actuarial survival of 73.4% 6
• For patients with EF ≤35%, postoperative mortality is approximately 4%, with long-term survival of 95.8% in selected patients 2
• Significant EF improvement (EF >40%) occurs in 82% of patients postoperatively, with mean post-operative EF improving to 35.2% 2, 6
• Patients with low EF experience higher incidence of postoperative respiratory failure compared to those with normal EF 2

Critical Pitfalls to Avoid

Do not defer surgery based solely on low EF:

• The survival benefit exists regardless of symptom severity in multivessel disease with low EF 1
• Do not perform CABG in patients with low EF who have poor target vessels or inability to achieve complete revascularization, as this negates the survival benefit 2
• Emergency CABG should not be performed within 3-7 days of acute MI unless ongoing ischemia with hemodynamic compromise exists, as surgical mortality is elevated during this window 4

Postoperative Medical Management

Guideline-directed medical therapy (GDMT) for heart failure is frequently underutilized:

• Only 52.6% of patients with HFrEF receive appropriate GDMT (heart failure beta-blocker plus renin-angiotensin inhibitor) preoperatively, with no significant increase at 1 year postoperatively 7
• Collaborative efforts between cardiac surgeons, heart failure cardiologists, and pharmacists are needed to optimize GDMT use and dose titration after CABG 7
• The combination of renin-angiotensin inhibitors, heart failure beta-blockers, and mineralocorticoid receptor antagonists should be maximized postoperatively 7