Importance of regurgitant fraction for left ventricular end-systolic wall stress to end-systolic volume ratio in patients with chronic mitral regurgitation.

End-systolic wall stress to end-systolic volume index (ESWS/ESVI) ratio is an index of myocardial contractility. In the presence of mitral regurgitation (MR), this ratio may be modified by the unloading effect of a leakage of flow into the low pressure left atrium. Therefore, to evaluate whether or not this ratio is an index of myocardial function in patients with MR, we compared the ratio with conventional measurements of myocardial performance in 11 patients with moderate to severe MR. The ESWS/ESVI ratio was 3.9 +/- 1.6 kdyn/cm5 per m2 in MR and slightly lower than the control value of 4.6 +/- 0.6 kdyn/cm5 per m2. The correlation between ESWS/ESVI ratio and ejection fraction was poor (r = 0.05, p:NS), while there was a close inverse correlation between the ratio and regurgitant fraction (r = 0.76, p less than 0.01). These results strongly suggest that ESWS/ESVI ratio is a better indicator of myocardial function than ejection fraction in MR; however, this ratio could be affected by not only the inotropic state of the ventricle, but also by the extent of mitral regurgitation.