DETERMINANTS OF POSTOPERATIVE LEFT-VENTRICULAR PERFORMANCE IN CHRONIC MITRAL REGURGITATION

Left ventricular (LV) systolic function is a major prognostic factor in patients with chronic mitral regurgitation after surgery. To determine whether there are indexes of preoperative LV function able to predict postoperative LV performance, 23 consecutive patients who underwent successful surgical correction of chronic mitral regurgitation were evaluated before and after surgery. At a mean follow-up of 20 +/- 16 mo, patients underwent echocardiography and radionuclide angiography, and were grouped according to the postoperative LV ejection fraction (LVEF). Sixteen patients with a LVEF greater-than-or-equal-to 45% constituted group A: they showed postoperative reduction of LV end-diastolic diameter (from 3.6 +/- 0.3 - 3.1 +/- 0.5 cm/m2; p < .001) and LV radius/thickness ratio (from 3.5 +/- 0.6 - 2.9 +/- 0.6; p < .01). In 7 patients (group B), the postoperative LVEF was < 45% and no significant change of the LV end-diastolic diameter or the radius/thickness ratio was observed. During follow-up, all group A patients remained asymptomatic or minimally symptomatic, whereas 2 group B patients died of refractory LV failure. Preoperative LV volumes, both at end-diastole and end-systole (151 +/- 38 vs. 116 +/- 23 mL/m2; p < .02 and 61 +/- 15 vs. 43 +/- 16 mL/m2; p < .02, respectively), were significantly greater in group B patients. These patients showed significantly higher regurgitant fraction (67 +/- 11 vs. 54 +/- 14%; p < .05), lower corrected forward LVEF (31 +/- 4 vs. 44 +/- 13%; p < .02), and reduced pressure/volume (1.5 +/- 0.3 vs. 2.6 +/- 0.8 mmHg.m2/mL; p < .01) and stress/volume (2.8 +/- 0.6 vs. 3.7 +/- 0.9 Kdyne.10(4)/mL; p < .05) ratios at end-systole as compared to group A patients. The specificity of these parameters to predict a low postoperative LVEF was, in general, fairly good, but their sensitivity was low. The most significant predictor of reduced postoperative LVEF in our patients was the combination of an end-diastolic volume greater than 125 mL/m2 and "corrected forward LVEF" less than 39%; this combination identifies all but one of the patients in group B with only two false positive results (86% sensitivity, 88% specificity). Therefore, in patients with chronic mitral regurgitation, the preoperative presence of a low normal or depressed "effective" ejection fraction, associated with enlarged end-diastolic volume, portends deterioration of left ventricular function and no reduction in LV chamber size.