Mitral Valve Repair or Replacement for Ischemic Mitral Regurgitation? The Italian Study on the Treatment of Ischemic Mitral Regurgitation (ISTIMIR)

Study Questions:

Is mitral valve replacement inferior to mitral valve repair for the treatment of chronic ischemic mitral regurgitation?

Methods:

Of 1,006 patients with chronic ischemic mitral regurgitation and impaired left ventricular (LV) function (ejection fraction <40%) operated on at 13 Italian institutions between 1996 and 2011, 298 (29.6%) underwent mitral valve replacement and 708 (70.4%) underwent 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 post-matching 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 = 0.32). Eight-year survival was 81.6% ± 2.8% and 79.6% ± 4.8% (p = 0.42), 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 for mitral valve repair and mitral valve replacement, respectively (p < 0.001). Actual freedom from all valve-related complications was 68.3% ± 3.1% versus 69.9% ± 3.3% for mitral valve repair and mitral valve replacement, respectively (p = 0.78). LV function did not improve significantly, and was comparable in the two groups postoperatively (36.9% vs. 38.5%, p = 0.66). At competing regression analysis, mitral valve repair was a strong predictor of reoperation (hazard ratio, 2.84; p < 0.001).

Conclusions:

The authors concluded that mitral valve replacement is a suitable option for patients with chronic ischemic mitral regurgitation and impaired LV function. It provides better results in terms of freedom from reoperation with comparable valve-related complication rates.

Perspective:

Data supporting the superiority of mitral valve repair over replacement predominantly are based on observational studies, with potential for substantial bias. Avoiding mitral valve replacement might be especially desirable among younger patients with myxomatous mitral valve degeneration (mitral valve prolapse), in part because of good anticipated long-term survival that leads to a choice between reoperation for structural deterioration of a bioprosthesis versus life-long warfarin with a mechanical prosthesis. However, two factors might differentiate patients with ischemic mitral regurgitation: 1) higher rates or recurrent mitral regurgitation after repair, owing to persistent leaflet restriction after reduction annuloplasty; and 2) shorter life expectancy in the setting of concomitant coronary artery disease and LV systolic dysfunction. These data do not address long-term clinical outcomes among patients operated on for ischemic mitral regurgitation. However, they do suggest that mitral valve replacement rather than repair lowers the need for reoperation (presumably for recurrent mitral regurgitation) without compromising rates of valve-related complications.

Clinical Topics: Anticoagulation Management, Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Valvular Heart Disease, Atherosclerotic Disease (CAD/PAD), Cardiac Surgery and Heart Failure, Cardiac Surgery and VHD, Acute Heart Failure, Interventions and Coronary Artery Disease, Interventions and Structural Heart Disease, Mitral Regurgitation

Keywords: Coronary Artery Disease, Mitral Valve Insufficiency, Warfarin, Heart Valve Prosthesis Implantation, Heart Diseases, Bioprosthesis, Mitral Valve Prolapse, Cardiology, Heart Failure, Heart Valve Diseases, Ventricular Function, Cardiac Surgical Procedures, Mitral Valve


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