Recovery of Left Ventricular Diastolic Function after Coronary Bypass Surgery

Abstract

Effects of myocardial revascularization in patients with preoperative left ventricular diastolic dysfunction have not been well characterized. The aim of this study was to evaluate the recovery of diastolic function following successful coronary artery bypass surgery. Forty-five patients with normal diastolic function were selected for comparison with 45 patients who had a pattern of diastolic dysfunction. Mitral flow peak velocity ratios and atrial filling fractions were measured by pulsed Doppler echocardiography 24 hours before surgery. Diastolic dysfunction was defined as a mitral flow peak velocity ratio of less than one. After coronary artery bypass graft surgery, patients who required hemodynamic support were excluded from further study. Group 1 consisted of 38 patients (mean age, 59 ± 9 years) with normal preoperative peak velocity ratios. Group 2 consisted of 33 patients (mean age, 52 ± 9) with preoperative diastolic dysfunction. In group 1, mitral flow peak velocity ratios decreased immediately after cardiopulmonary bypass and persisted for 24 hours, returning to normal at 72 hours. In group 2, peak velocity ratios decreased immediately after cardiopulmonary bypass and persisted for 10 days. Similar changes occurred in atrial filling fractions in the 2 groups. These findings indicate that recovery of left ventricular diastolic function is prolonged in patients with preoperative dysfunction, which may reflect the time required for reversal of the effects of chronic myocardial ischemia.