PROLONGED MYOCARDIAL HIBERNATION EXACERBATES CARDIOMYOCYTE DEGENERATION AND IMPAIRS RECOVERY OF FUNCTION AFTER REVASCULARIZATION

Objectives. We sought to define the effects of time on contractile fun ction, morphology and functional recovery after coronary revasculariza tion in patients with dysfunctional but viable (hibernating) myocardiu m. Background. Functional recovery after coronary artery bypass graft surgery in patients with chronic myocardial hibernation is incomplete or delayed. The proposed cause is a progressive temporal degeneration of cardiomyocytes. Methods. In 32 patients with multivessel coronary d isease, regional wall motion analysis was performed in hypoperfused bu t metabolically active areas before and 6 months after bypass surgery. During bypass surgery, transmural biopsy samples were obtained from t he center of the hypokinetic zone for light and electron microscopic a nalyses. The proposed duration of myocardial hibernation was retrospec tively assessed. Results. Patients with a subacute hibernating conditi on (<50 days) demonstrated a higher preoperative ejection fraction (EF , 50 +/- 8%), and a better preserved wall motion (WM) in the supraapic al wall (-1.4 +/- 0.1) than did patients with intermediate-term (>50 d ays, EF 37 +/- 9%, p < 0.05; WM-2.4 +/- 1.5, p = 0.08) or chronic (>6 months, EF 40 +/- 14%, WM-2.7 +/- 0.9, p < 0.005) ischemia. Structural degeneration correlated with the duration of ischemia (r = 0.56, p < 0.05). Postoperative recovery of function was enhanced in patients wit h a short history of hibernation compared with patients with an interm ediate-term or chronic condition (EF 60 +/- 10% vs. 40 +/- 10%, p < 0. 001, and vs. 47 +/- 14%, p < 0.05). Conclusions. Hibernating myocardiu m exhibits time dependent deterioration due to progressive structural degeneration with enhanced fibrosis. Early revascularization should be attempted to salvage the jeopardized tissue and improve postoperative outcome. (C)1998 by the American College of Cardiology.