The effects of body mass index on long-term outcomes and cardiac remodeling following mitral valve repair surgery.

Abstract

Previous literature has demonstrated equivalent or improved survival post mitral valve (MV) surgery amongst patients with obesity when compared to their normal-weight counterparts. This relationship is poorly understood and the impact of body mass index (BMI) on cardiac remodeling has not been established. In this retrospective, single-center study, we sought to identify the impact that BMI may have on long-term outcomes and cardiac remodeling post-MV repair. Outcomes were compared between patients of varying BMI undergoing MV repair between 2004 and 2018. The primary outcome was mortality and secondary outcomes included stroke, myocardial infarction, reoperation of the MV, rehospitalization, and cardiac remodeling. A total of 32 underweight, 249 normal weight, 249 overweight, 121 obese, and 50 morbidly obese patients were included in this study. Underweight patients had increased mortality at longest follow-up. Patients with morbid obesity were found to have higher rates of readmission for heart failure. Only underweight patients did not demonstrate a significant reduction in LVEF. Patients with normal weight and overweight had a significant reduction in left atrial size, and patients with obesity had a significant reduction in MV area. An obesity paradox has been identified in cardiac surgery. While patients with obesity have higher rates of comorbidities preoperatively, their rates of mortality are equivalent or even superior to those with lower BMI. The results of our study confirm this finding with patients of high BMI undergoing MV repair demonstrating equivalent rates of morbidity to their normal BMI counterparts. While the obesity paradox has been relatively consistent in the literature, the understanding of its cause and long-term impacts are not well understood. Further focused investigation is necessary to elucidate the cause of this relationship.