1356998 - Sex differences in primary mitral regurgitant volumes at the same regurgitant fraction prior to mitral intervention

The institutional review board approved a retrospective review of MRI patients with waiver of consent. A cohort of 26 patients having an MRI between 1/1/2017 and 8/31/2022 to evaluate mitral insufficiency severity that then proceeded to mitral intervention was identified. The correlation between regurgitant fraction and regurgitant volume for men and women was assessed using simple linear regression. The linear regression equations were then used to determine the correlating regurgitant volume for specific regurgitant fraction values. Comparisons were made using analysis of covariance, unpaired t-test, and chi-square.

Results: Of the 26 patients, 11 (42%) were women. Men had a significantly larger left ventricular end-diastolic volume, end-systolic volume, and stroke volume. Compared to normative data for left ventricular end-diastolic volume index, men’s’ values were 21% larger than the upper limit of normal, while women’s were 10% larger (5). Women had significantly faster heart rates than men (77±18 bpm vs. 64±13 bpm; p=.05). While there was no difference in regurgitant fraction between men and women (49±10% vs. 46±8%; p=.42), men had significantly larger regurgitant volumes (79±17 ml vs. 51±14 ml; p =.0002). Simple linear regression identified similar slopes between men and women, but with quite different y-intercept values (ANCOVA P< .0001) (figure 1). A regurgitant fraction of 40% correlated to a regurgitant volume of 67 ml in men and 42 ml in women, while a regurgitant fraction of 50% correlated to 81 ml in men and 56 ml in women. Indexing the regurgitant volume to body surface area provided a partial explanation for the difference in regurgitant volume between men and women, but the y-intercept values still differed significantly (ANCOVA P=.0007).

Conclusion:

In primary mitral insufficiency patients undergoing mitral intervention, men and women have similar regurgitant fractions, but men have significantly larger regurgitant volumes. In response to the increased preload of mitral insufficiency it appears men dilate their left ventricle more than women, while women compensate with increased heart rate. Regurgitant fraction provides a sex-independent variable for quantifying mitral insufficiency severity.