Impact of prosthesis-patient mismatch on late outcomes after bioprosthetic mitral valve replacement for mitral regurgitation

Negative impact of prosthesis-patient mismatch on long-term survival after valve replacement has been reported. However, the effect of prosthesis-patient mismatch after bioprosthetic mitral valve replacement has not yet been well examined. The purpose of this study was to investigate the effect of prosthesis-patient mismatch on late outcomes after bioprosthetic mitral valve replacement for mitral regurgitation. A total of 181 patients underwent bioprosthetic mitral valve replacement between April 2008 and December 2016. After excluding patients with mitral stenosis and those with incomplete data, 128 patients were included in the study. Postoperative transthoracic echocardiography was performed before discharge for all patients and the effective orifice area of bioprosthetic mitral valve was calculated using the formula: 220/pressure half-time, and the effective orifice area index was calculated by the formula: effective orifice area/body surface area. Prosthesis-patient mismatch was defined as a postoperative effective orifice area index ≤ 1.2 cm²/m². The characteristics and outcomes were compared between the groups. There were 34 patients (26.6%) with prosthesis-patient mismatch and 94 patients (73.4%) without prosthesis-patient mismatch. There were no significant differences in the in-hospital mortality and morbidities. Multivariable analysis showed that prosthesis-patient mismatch was an independent predictor of late mortality (hazard ratio 3.38; 95% confidence interval 1.69–6.75; p = 0.001) and death from heart failure (hazard ratio 31.03, 95% confidence interval 4.49–214.40, p < 0.001). Prosthesis-patient mismatch at discharge after mitral valve replacement for mitral regurgitation was associated with long-term mortality and death from heart failure.