Background: Obesity has tripled worldwide over the past 50 years. Existing evidence depicts conflicting relationships between body mass index and operative risk in cardiac surgery. Some large analyses have showed a shaped relationship between obesity and peri-operative mortality; others have found an inverse relationship, a so-called obesity paradox.
Objectives: We aimed to outline the effects of obesity on early outcome in minimally invasive mitral valve (MV) surgery.
Methods: One-thousand-seven-hundred-twenty consecutive patients who underwent mini-thoracotomy MV surgery at a single tertiary care academic centre since 2006 were retrospectively analysed. Multivariable logistic regression served to identify predictors of 30-day outcomes.
Results: Obesity (n=149/1695, 8.8%) was predictive of 30-day mortality (5.4% vs. 1.8%; p=0.010; odds ratio [OR] 3.14, 95% CI 1.36-7.27), but not when excluding patients with associated coronary and/or extracardiac arteriopathy (n=255/1695, 15%). Conversely, obesity was the sole predictor of death in this subgroup (4.3% vs. 1.9%; p=0.015; OR 3.65, 95% CI 1.01-13.17). Other predictors in the entire cohort were age, creatinine, reoperation and arteriopathy. Obese patients had more comorbidities and less degenerative MV prolapse, and parallel higher probability of MV replacement (p<0.001). Cardiopulmonary bypass time, but not cardioplegic arrest time, was longer (p=0.007). Morbidity, primarily driven by respiratory and wound complications, was also higher, with longer intensive care and hospital length-of-stay (p<0.001).
Conclusions: Obesity confers additional operative risk in MV surgery despite a minimally invasive approach. However, increased risk is confined to patients with concomitant arteriopathy and atherosclerotic burden, for whom weight loss is advisable in a nonurgent scenario.
Keywords: Atherosclerotic burden; BMI; Metabolic disorders; Minimally invasive surgery; Mitral valve; Obesity paradox.
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