[The influence of left ventricular function on surgical risk in mitral stenosis]

The influence of left ventricular (LV) function on surgical risk was assessed in 98 patients with mitral stenosis (MS) using echocardiographic studies including a dobutamine test in 42 cases. Intraoperative LV myocardial biopsy was also performed in 24 cases. Preoperatively, depressed LV function [% fractional shortening (%FS) less than or equal to 27%] was observed in 21 patients (21%). Seven patients had postoperative LV failure, five of whom had preoperative depression of LV function. Among these five patients, three had low cardiac output; and in the other two preoperative %FS was severely depressed. In cases of poor responses to preoperative dobutamine, postoperative improvement in %FS and the cardiac index were not as marked in the good-response group, and some of these patients had LV failure postoperatively. Percent fibrosis of the LV myocardium, which was demonstrated by intraoperative biopsy, correlated negatively with preoperative %FS, and %fibrosis was greater in the group responding poorly to dobutamine administration, especially in patients with postoperative LV failure. These results suggest that some patients with MS were developing LV failure postoperatively due to impaired myocardium. Myocardial fibrosis seemed to be an important causative factor in these patients. Preoperative evaluation utilizing dobutamine administration is useful in screening for high-risk patients.