Impact of obesity on outcomes of minimally invasive mitral valve repair for mitral regurgitation

Objective: Obesity impacts the outcomes of cardiac surgeries, contributing to substantial morbidity. The effect of obesity on outcomes in patients undergoing minimally invasive mitral valve repair for severe mitral regurgitation is not well understood. This study aims to compare the outcomes of obese patients with those of normal-weight patients undergoing this procedure.

Methods: This single-center, retrospective analysis included patients with severe mitral regurgitation and body mass index (BMI) either within the normal range (19–25 kg/m²) or classified as obese (BMI ≥30 kg/m²). All patients underwent minimally invasive mitral valve repair via a right lateral mini-thoracotomy between 1999 and 2022. Clinical outcomes were assessed after propensity score matching. The primary outcome was overall survival at 5 and 10 years.

Results: A total of 2,512 patients met the inclusion criteria for BMI (1,896 normal weight and 616 obese). After matching, 475 pairs of patients were analyzed. Matched patients were predominantly male (65%), with a median age of 61 years. The median (interquartile range) body weight was 69 (62–75) kg in the normal-weight group and 96 (89–105) kg in the obese group (p=0.023). The groups were similar in baseline characteristics, except for the incidence of hypertension (44% in the normal-weight group vs. 22% in the obese group, p<0.001). There were 5 conversions to sternotomy in the normal-weight group and 7 in the obese group (p=0.771). Obese patients had longer median surgery and cardiopulmonary bypass times compared to normal-weight patients (175 [145–208] vs. 170 [140–195] minutes, p=0.005 and 125 [104–152] vs. 122 [97–145] minutes, p=0.037), but no significant difference in aortic cross-clamping time. There were no differences in perioperative or early clinical outcomes, including wound infections. However, obese patients had a longer median hospital stay (14 [11–18] vs. 13 [10–17] days, p=0.027). At 5 years, there was no significant difference in echocardiographic parameters or the need for mitral valve reoperation (6 cases in the normal-weight group and 14 in the obese group, p=0.20). The actuarial 5- and 10-year survival rates were 87% and 73% in the normal-weight group, and 90% and 78% in the obese group, respectively (p=0.35).

Conclusions: Minimally invasive mitral valve repair for severe mitral regurgitation yields similar long-term outcomes in obese patients as in those with normal weight.

Figure 1. Kaplan-Meier survival analysis in patients with normal weight or obesity undergoing minimally invasive mitral valve repair.