(P180) SURVIVAL AND OUTCOMES OF CORONARY ARTERY BYPASS SURGERY IN PATIENTS WITH EXTREMELY LOW EJECTION FRACTION (LESS THAN 20%) - A SYSTEMATIC REVIEW AND META-ANALYSIS

Background: Lower ejection fraction (EF) has been identified as a risk factor for increased mortality and morbidity following coronary artery bypass grafting (CABG). Patients with extremely low EF (≤20%) have been historically underrepresented in studies of surgical revascularization, and the role of CABG for these patients with heart failure remains debated in the current era of excellent outcomes following the placement of durable mechanical circulatory support. The aim of this systematic review is to quantitatively aggregate published outcomes and potential benefits of CABG for these patients.

METHODS AND RESULTS: We performed a librarian-assisted systematic search of MEDLINE, EMBASE, and CENTRAL via OVID for both randomized control trials and cohort studies involving patients with EF ≤ 20% undergoing CABG, including results from 1995 to December 2023, with no language restrictions. We also included EF ≤ 20% subgroups that were part of larger studies. We performed random-effects prevalence meta-analysis using the meta library in R. Outcome prevalence was logit-transformed and pooled using a generalised linear mixed-effects model. The presence of heterogeneity was assessed using Cochran’s Q test with a significance of P < 0.10 following Cochrane Handbook recommendations and further quantified using I2 statistics. A total of 29 studies involving 6523 patients were included in this analysis. The pooled prevalence of perioperative mortality was 9% (CI: 0.08-0.11, I2=45%), with no temporal correlation on visual inspection (Figure 1). Postoperative myocardial infarction and stroke prevalence were 2% (CI: 0.01-0.04, I2=53%) and 3% (CI: 0.02-0.03, I2=0%), respectively. Low cardiac output syndrome definition varied across studies, and its pooled prevalence was 16% (CI: 0.11-0.22, I2=84%), with corresponding postoperative mechanical circulatory support requirement at 9% (CI: 0.03-0.21, I2=90%). The pooled actuarial 5-year survival rate was 74% (CI: 0.69-0.78, I2=37%), with no temporal relationship on visual inspection (Figure 2).

Conclusion: In this meta-analysis of mostly cohort studies, we demonstrate that CABG for extremely low ejection fraction (≤ 20%) patients have higher than average perioperative mortality and morbidity risk, yet may derive considerable long-term survival benefit, comparable to that of durable Left Ventricular Assist Device placement in selected patients. More long-term data is needed in this patient population to elucidate the relative risks and benefits of CABG versus advanced heart failure therapies at 5 years and beyond.