Prognostic value of the amount of dysfunctional but viable myocardium in revascularized patients with coronary artery disease and left ventricular dysfunction

Abstract

Objectives. The purpose of our study was to assess the prognostic importance of the amount of dysfunctional but viable myocardium in revascularized patients with coronary artery disease (CAD) and left ventricular (LV) dysfunction.Background. The amount of dysfunctional but viable myocardium predicts the functional improvement after revascularization and may offer more precise risk stratification of patients referred for bypass surgery or coronary angioplasty.Methods. Two hundred and seventy-four consecutive patients with CAD and LV ejection fraction ≤40% underwent low-dose dobutamine echocardiography for viability assessment. One hundred and thirty-three of them were revascularized using either coronary artery bypass surgery (118 patients) or coronary angioplasty (15 patients) and entered this study. To quantify the amount of dysfunctional but viable myocardium, wall motion was scored using 16-segment model. The dysfunctional segments were defined as viable if they exhibited improvement in their thickening by at least 1 grade with dobutamine infusion. The patients were followed up for a mean period of 20 ± 12 months (range, 2 to 48) for cardiac mortality and nonfatal cardiac events including myocardial infarction, unstable angina pectoris requiring hospitalization and hospitalization for heart failure. Standard follow-up echocardiography was performed 3 to 6 months after revascularization.Results. Twenty-nine patients exhibited a large amount of dysfunctional but viable myocardium (≥6 segments, group A), 60 patients had a small amount of dysfunctional but viable myocardium (2 to 5 segments, group B) and 44 patients were found to have dysfunctional myocardium irreversibly damaged (group C). Similar prerevascularization LV ejection fractions of 35% ± 5%, 34% ± 4%, 36% ± 4% in groups A, B and C increased to 47% ± 6% (p < 0.01 vs. baseline, p < 0.01 vs. groups B and C), to 40% ± 5% (p < 0.01 vs. baseline) and to 37% ± 6% (p = NS vs baseline), respectively, after revascularization. The greatest functional improvement after revascularization in group A patients was accompanied by a lower rate of cardiac events during follow-up (2 vs. 18 in group B, p < 0.05, and vs. 17 in group C, p < 0.01) and better cardiac event-free survival according to Kaplan–Meier survival analysis (p < 0.05 vs. groups B and C, respectively).Conclusion. In revascularized patients with CAD and moderate or severe LV dysfunction, the presence of a large amount of dysfunctional but viable myocardium identifies patients with the best prognosis.