Patient–prosthesis mismatch in mitral annuloplasty for degenerative mitral regurgitation: an ignored issue

OBJECTIVES: Elevated postoperative transmitral gradient (TMG), partially induced by a small annuloplasty ring, is associated with late atrial fibrillation (AF) after mitral valve repair. Here, we aimed to provide the optimal cut-off of prosthetic ring size to reduce patient-prosthesis mismatch (PPM) after mitral annuloplasty. METHODS: From 2006 to 2017, 262 patients who underwent mitral valve repair for degenerative pathologies were retrospectively studied. The relationships of body surface area (BSA)-indexed prosthetic orifice area (POAi)-postoperative TMG and POAi-late AF were tested using regression curves and receiver operating characteristic curves, respectively. The optimal cut-off of POAi predictive of late AF was used to define PPM. Baseline and follow-up data of patients with and without PPM were compared in propensity score-matched cohorts. RESULTS: In-hospital mortality was 0. Late AF was observed in 9.2% (24/262) patients during a median follow-up of 3.8 years. An exponential model was best fitted based on the POAi-postoperative TMG relationship (P < 0.001). Using late AF as the dependent variable, the optimal cut-off for PPM was POAi ≤2.28 cm2/m2 (c-statistic 0.71; sensitivity 0.61; specificity 0.80; P < 0.001). PPM was identified in 113 (43.1%) patients. After propensity score matching, the estimated 5-year rate of late AF was significantly higher in PPM patients than in non-PPM patients (24% vs 5%; P < 0.001). CONCLUSIONS: Postoperative TMG increases significantly with a small POAi for full ring annuloplasty. A patient's BSA should be considered in addition to valvular dimensions during the selection of a proper ring size to reduce PPM-related AF.