Outcomes of Coronary Artery Bypass Surgery in Patients with Reduced Left Ventricular Function and Hibernating Myocardium

Abstract

Abstract

Objective:
The medium-term functional recovery of the left ventricle (LV) and overall prognosis following coronary artery bypass grafting (CABG) in patients with markedly reduced ventricular function and hibernating myocardium (HM) remains insufficiently defined. This study prospectively investigated postoperative outcomes in patients with severe LV impairment and evidence of myocardial hibernation.

Methods:
A total of 120 consecutive patients with significant LV dysfunction and HM, confirmed through dobutamine stress echocardiography and rest-redistribution thallium-201 imaging, were included. The mean age was 60 ± 9 years (range 31–77), and the mean preoperative ejection fraction (LVEF) was 28 ± 9% (range 25–40%). LV function was evaluated by echocardiography intraoperatively, before discharge, at three months, one year, and annually thereafter. Predictors of survival were analyzed using univariate and multivariate statistical methods.

Results:
Early mortality was 1.6% (n=2), and 12.5% (n=15) died during late follow-up, predominantly from heart failure. Actuarial survival was 80 ± 6% at five years and 60 ± 9% at eight years. LVEF improved significantly following surgery (from 28 ± 9% to 40 ± 2%, p < 0.01), although this early gain progressively diminished over time, with mean LVEF decreasing to 33 ± 9% at three months, 32 ± 8% at one year, and 30 ± 9% at eight years. Patients who showed minimal early recovery of LV function experienced a more rapid decline in EF and more frequent recurrence of heart failure. Freedom from heart failure was 82 ± 5% at four years and 60 ± 8% at eight years. Advanced preoperative NYHA class and older age independently predicted poorer long-term survival, whereas preoperative angina and use of arterial grafts did not significantly affect long-term outcomes.

Conclusion:
CABG in patients with hibernating myocardium and severely depressed LV function results in meaningful early improvement in ventricular performance and generally favorable overall prognosis. However, the functional benefit tends to diminish over time. Older age, advanced heart failure at presentation, and limited perioperative improvement in LVEF are associated with less favorable long-term outcomes.

Keywords:
Coronary artery bypass grafting; Hibernating myocardium; Left ventricular dysfunction; Ischemic cardiomyopathy; Postoperative outcomes; Long-term survival; Ventricular function recovery