Guidelines suggest using a regurgitant fraction of 50% and regurgitant volume of 60 ml for determination of severe mitral insufficiency. Recent MRI data has suggested that a regurgitant fraction of 40% defines severe primary mitral insufficiency. We sought to determine whether there were gender differences in primary mitral regurgitant volumes for regurgitant fractions of 40% and 50%. A database search identified 394 patients that had MRI with a mitral regurgitant volume� � �10 ml or a study indication of mitral insufficiency. Chart review identified 97 patients with primary mitral insufficiency. Of these patients, 53 (54%) were women. Men had significantly larger left ventricular volumes, myocardial mass, stroke volumes and mitral regurgitant volumes (37 ±�25 ml vs. 24 ±�12 ml). The difference in regurgitant fraction between genders was not significant (27 ±�14% vs. 24 ±�11%; p-value�=�0.24). Regurgitant fraction and regurgitant volume had a strong linear correlation in both men (r�=�.95) and women (r�=�.92). Despite similar linear correlations, the slope-intercept equations differed significantly between men and women (p�<�.001). A regurgitant fraction of 40% correlated with a regurgitant volume of 59 ml in men and 39.5 ml in women, while a regurgitant fraction of 50% correlated with a regurgitant volume of 76.2 ml in men and 49.6 ml in women. Regurgitant fraction, determined by cardiac MRI, provides a gender independent assessment of primary mitral insufficiency, and suggests that regurgitant volume thresholds for severe primary mitral insufficiency may be lower in women.
