Influence of Direct Myocardial Revascularization on Left Ventricular Asynergy and Function in Patients with Coronary Heart Disease

Abstract

The influence of successful aortocoronary artery bypass surgery on left ventricular asynergy and dysfunction was studied by hemodynamic and angiographic methods in 29 patients with coronary artery disease. Eight patients had the preinfarction syndrome, 10 patients had chronic ischemia without previous infarction, and 11 patients had chronic ischemia with previous infarction. LV asynergy was present preoperatively in 12 of the 18 patients in the first two groups. Marked improvement occurred in all and a normal wall motion was restored in the majority following surgery. More pronounced improvement was noted in the preinfarction syndrome as compared to the group with chronic ischemia and no previous infarct. The ejection fraction was reduced in 12 of the 18 patients in these two groups and significant improvement was observed postoperatively [0.45 ± 0.03 (sem) to 0.74 ± 0.03]. Increase in ejection fraction was primarily due to a decrease in the end-systolic volume (71 ± 12 to 23 ± 4 ml/m²). The end-diastolic volume was only slightly reduced (114 ± 12 to 97 ± 9 ml/m²). Left ventricular end-diastolic pressure fell from 15 ± 1 to 10 ± 1 mm Hg. In nine of 11 patients who had previous myocardial infarction, abnormal wall motion was present preoperatively. Following surgery, some abnormalities of wall motion persisted in the areas of known infarction, although significant improvement of wall motion occurred in the noninfarcted segments. The ejection fraction was reduced in seven of these 11 patients and improved postoperatively. (0.44 ± 0.05 to 0.59 ± 0.05). The end-systolic volume decreased from 57 ± 5 to 41 ± 6 ml/m², and the end-diastolic volume was unchanged (106 ± 5 to 108 ml/m²). Left ventricular end-diastolic pressure fell from a mean value of 17 ± 3 to a mean value of 10 ± 2 mmHg following successful surgery. These findings are consistent with improved pump function and were associated with improvement in indices of contractile state. The observations indicate that significant improvement in ventricular wall motion and pump function occurs in patients with obstructive coronary disease following successful aortocoronary artery bypass surgery even in the presence of old myocardial infarction. Since the patients of the present study all had normal initial end-diastolic volumes, however, similar beneficial results might not occur in patients with cardiomegaly and more severe heart failure.