Mitral valve repair or replacement for ischemic mitral regurgitation? The Italian Study on the Treatment of Ischemic Mitral Regurgitation (ISTIMIR)

Abstract

Objective: It is uncertain whether mitral valve replacement is really inferior to mitral valve repair for the treatment of chronic ischemic mitral regurgitation. This multicenter study aimed at providing a contribution to this issue.

Methods: Of 1006 patients with chronic ischemic mitral regurgitation and impaired left ventricular function (ejection fraction < 40%) operated on at 13 Italian institutions between 1996 and 2011, 298 (29.6%) underwent mitral valve replacement whereas 708 (70.4%) received mitral valve repair. Propensity scores were calculated by a nonparsimonious multivariable logistic regression, and 244 pairs of patients were matched successfully using calipers of width 0.2 standard deviation of the logit of the propensity scores. The postmatching median standardized difference was 0.024 (range, 0-0.037) and in none of the covariates did it exceed 10%.

Results: Early deaths were 3.3% (n = 8) in mitral valve repair versus 5.3% (n = 13) in mitral valve replacement (P = .32). Eight-year survival was 81.6% ± 2.8% and 79.6% ± 4.8% (P = .42), respectively. Actual freedom from all-cause reoperation and valve-related reoperation were 64.3% ± 4.3% versus 80% ± 4.1%, and 71.3% ± 3.5% versus 85.5% ± 3.9 in mitral valve repair and mitral valve replacement, respectively (P < .001). Actual freedom from all valve-related complications was 68.3% ± 3.1% versus 69.9% ± 3.3% in mitral valve repair and mitral valve replacement, respectively (P = .78). Left ventricular function did not improved significantly, and it was comparable in the 2 groups postoperatively (36.9% vs 38.5%, P = .66). At competing regression analysis, mitral valve repair was a strong predictor of reoperation (hazard ratio, 2.84; P < .001).

Conclusions: Mitral valve replacement is a suitable option for patients with chronic ischemic mitral regurgitation and impaired left ventricular function. It provides better results in terms of freedom from reoperation with comparable valve-related complication rates.