Impact of left ventricular ejection fraction on hospital and long term outcomes after coronary artery bypass graft surgery

Abstract

Abstract Background Coronary artery bypass surgery is recommended for patients with extensive coronary artery disease and severely impaired left ventricular ejection fraction (LVEF). Short term clinical outcomes improved due to advanced surgical techniques and perioperative management. Objective To study the impact of pre-operative left ventricular ejection fraction (LV EF) on clinical outcomes during postoperative hospitalization and for 5 years follow up. Methods The study was a retrospective analysis of patients underwent CABG at our tertiary care hospital between January 2016 and August 2020.The primary outcome was mortality and the secondary outcomes included acute cerebrovascular stroke, length of hospitalization, subsequent revascularization, and heart failure. Results The study included 410 patients with a median age of 60 (55–68) years, a hospital mortality of 2.7%, postoperative stroke of 7.6%, acute kidney injury (AKI) of 25.6% and new need dialysis of 5.9%. The patients were divided into 4 groups: 75 (18.3%) patients had LV EF less than 35%, 88 (21.5%) had LV EF 35–45%, 106 (25.9%) had LV EF 45–55% and 141 (34.4%) had LV EF more than 55% with significant differences in frequencies of chronic kidney disease (29.3% vs. 40.9% vs. 23.6% vs. 24.1%, p=0.026), prior cerebral stroke (9.3% vs. 11.4% vs. 8.5% vs. 1.4%, p=0.015), Peripheral vascular disease (8% vs. 18.2% vs. 4.7% vs. 12.1%, p=0.019) respectively. The hospital mortality occurred in (6.7% vs. 0% vs. 0.9% vs. 3.5%, p=0.03), acute cerebrovascular stroke occurred in (14.7% vs. 6.8% vs. 3.8% vs. 7.1%, p=0.031), AKI occurred in (36% vs. 43.2% vs. 17.9% vs. 14.9%, p<0.001), new dialysis was used in (12% vs. 5.7% vs. 1.9% vs. 5.7%, p=0.04), ICU stay was [5 (3–7) vs. 4 (3–11) vs. 4 (3–5) vs. 3 (2–5), p<0.001], post ICU stay was [6 (3–10) vs. 5 (4–8) vs. 4 (3–6) vs. 4 (3–6), p=0.009] in patients with LV EF <35%, LV EF 35–45%, LV EF 45–55% and LV EF >55% respectively. Mortality during follow up occurred in (20% vs. 4.5% vs. 2.8% vs.4.3%, p<0.001), stroke occurred in (8% vs. 4.5% vs.0.9 5% vs. 2.8%, p=0.031), revascularization was done in (2.7% vs. 23.9% vs. 18.9% vs. 12.8%, p=0.009) and readmission with heart failure occurred in (52% vs. 34.1% vs. 10.4% vs. 4.3%, p<0.001) in patients with LV EF <35%, LV EF 35–45%, LV EF 45–55% and LV EF >55% respectively. Conclusion Reduced LV EF was associated with increased hospital mortality, frequent morbidities, and prolonged hospitalization after CABG with higher composite rate of death, stroke, heart failure at 5 years compared with normal or mildly reduced LV EF. Funding Acknowledgement Type of funding sources: None.