Abstract
<title>Abstract</title> <p>Background Body mass index (BMI) measures obesity and underweight, which affect mortality in many populations. We studied how BMI influences mortality and complications after total thoracoscopic isolated valve surgery (TTIVS), a minimally invasive cardiac procedure. Methods We analyzed 2162 patients who underwent TTIVS at our institution from January 2018 to June 2023. We grouped them by BMI: underweight (≤ 18.4 kg/m2), normal weight (18.5 to 24.9 kg/m2), overweight (25.0 to 29.9 kg/m2), or obese (≥ 30 kg/m2). We used statistical methods to examine the association of BMI with in-hospital mortality, adjusting for confounders. We also compared postoperative complications and length of stay among BMI groups. Conclusion The in-hospital mortality rate was 2.27% (49/2162). The mortality rates for underweight, normal weight, overweight, and obese groups were 5.36% (6/112), 1.50% (15/1001), 1.57% (13/829), and 6.82% (15/220), respectively. Underweight and obesity were associated with higher mortality than normal weight (adjusted HR: 4.614; 95% CI: 1.701–12.518; p = 0.003 for underweight; adjusted HR: 2.897; 95% CI: 1.319–6.364; p = 0.008 for obese), while overweight was not (adjusted HR: 1.221; 95% CI: 0.579–2.573; p = 0.600). BMI and mortality had a U-shaped relationship, with the lowest risk at 24.2–26.3 kg/m2. Underweight and obese groups had more respiratory and cardiocerebral complications, but similar length of stay. Conclusion We observed a U-shaped association between BMI and mortality after TTIVS, with higher risk in underweight and obese patients. This suggests BMI could inform risk assessment for TTIVS, though causality is not implied. Further research should explore mechanisms and strategies to improve outcomes for these high-risk groups.</p>