Randomized trial comparing partial versus complete chordal-sparing mitral valve replacement: effects on left ventricular volume and function.

Objective: The merits of retaining the subvalvular apparatus during mitral valve replacement for chronic mitral regurgitation have been demonstrated in numerous retrospective clinical investigations but not in a randomized study. In this report we analyzed the early and late effects of complete versus partial chordal preservation on left ventricular mechanics.

Methods: Forty-seven patients undergoing isolated surgical correction of mitral insufficiency were prospectively randomized to either total or partial chordal-sparing mitral valve replacement. Complete data from 36 patients were available for analysis. Of these individuals, 15 had preservation of the posterior leaflet only (P-MVR group), and 21 had complete preservation of all chordal structures (C-MVR group). Echocardiography was performed preoperatively, at the time of discharge, and after 1 year to determine dimensions, wall stress, left ventricular mass, and ejection function.

Results: End-diastolic volume decreased in both groups initially but continued to decline only in the C-MVR cohort. Similarly, although end-systolic volume decreased over time with total chordal preservation, no notable changes were observed in the P-MVR group. In the C-MVR group, end-systolic stress decreased initially but rose slightly by 1 year. In contrast, end-systolic stress remained unchanged at discharge in the P-MVR group and increased at 1 year. In terms of systolic performance, ejection fraction declined after surgical intervention with partial chordal-sparing techniques and did not improve by 1 year. Ejection fraction returned to the preoperative level after an initial decrease in the C-MVR group. Finally, left ventricular mass was reduced in the C-MVR cohort versus no change in the P-MVR group.

Conclusion: Complete retention of the mitral subvalvular apparatus during mitral valve replacement confers a significant early advantage by reducing left ventricular chamber size and systolic afterload compared with partial chordal preservation. Furthermore, left ventricular ejection performance continues to improve over time, probably because of more favorable left ventricular remodeling.