Importance of Subvalvular Preservation and Early Operation in Mitral Valve Surgery

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Abstract
Background Mitral valve replacement (MVR) has a high mortality and morbidity. It has been suggested that preservation of the subvalvular apparatus and more optimal timing of surgery might improve outcome. Methods and Results We performed a retrospective study of 612 consecutive patients who underwent mitral valve repair or replacement: 226 patients had repair, 68 had replacement with subvalvular preservation (MVR/SVP), and 318 had replacement without subvalvular preservation (MVR/NoSVP). Baseline characteristics were most unfavorable in the repair group with respect to age ( P =.002) and in the repair and MVR/SVP groups with respect to NYHA functional class and left ventricular function ( P =.044). Thirty-day mortality was lower in the repair (1.8%, P =.046) and MVR/SVP (1.5%, P =NS) groups than the MVR/NoSVP group (5.0%). Overall survival at 7 years was better in the repair (71.2±5.6%, P =.022) and MVR/SVP (66.2±12.4%, P =.017) groups than the MVR/NoSVP group (63.5±3.4%). Myocardial failure caused 66 of 107 complication-related deaths. Multivariate analysis confirmed independent beneficial effects of repair on 30-day mortality (odds ratio, 0.27, P <.05) and of repair and MVR/SVP on overall mortality (hazard ratios, 0.43, P <.001 and 0.40, P <.05, respectively) and complication-related death (hazard ratios, 0.38, P <.001 and 0.35, P <.05, respectively). Preoperative NYHA class III or IV symptoms and left ventricular impairment were independent risk factors for death and myocardial failure. Conclusions Mitral valve repair is superior to replacement. If repair is not feasible, the subvalvular apparatus should be preserved. Early surgery before the development of severe symptoms and demonstrable left ventricular impairment is also needed to optimize outcome.