Isolated Robotic Mitral Valve Replacement Across Body Mass Index Categories: Early Perioperative Outcomes

Background: Obesity may pose additional technical and perioperative challenges in robotic mitral valve surgery. This study evaluated early perioperative outcomes of isolated robotic mitral valve replacement (MVR) across BMI categories. Methods: We retrospectively analyzed 146 patients who underwent isolated robotic MVR at a single center, categorized into BMI categories of <25 kg/m² (n = 60), 25.0-29.9 kg/m² (n = 38), or ≥30 kg/m² (n = 48). Preoperative characteristics, operative variables, and early postoperative outcomes were compared among groups. The study was exploratory. Four clinically selected outcomes, cardiopulmonary bypass time, ventilation duration, hospital length of stay, and postoperative left ventricular ejection fraction, were evaluated using adjusted median quantile regression with bootstrap 95% confidence intervals, and multiplicity across postoperative outcomes was addressed using the Benjamini-Hochberg false discovery rate. Results: Patients with BMI ≥ 30 kg/m² were older and had a higher prevalence of diabetes and higher EuroSCORE II values. Unadjusted comparisons of cardiopulmonary bypass and aortic cross-clamp times, conversion to sternotomy, ventilation duration, intensive care unit and hospital length of stay, drainage volume, and transfusion requirements yielded p values > 0.05. In adjusted analyses of the four selected outcomes, all 95% confidence intervals for the BMI-group estimates included zero. Pneumonia was numerically more frequent in patients with BMI ≥ 30 kg/m² (10.4% vs. 2.6% and 1.7%), but the estimates were imprecise. In-hospital mortality was low, with one death overall. Only eight patients had BMI ≥ 35 kg/m². Conclusions: Among patients considered suitable for robotic MVR, the adjusted estimates showed no statistically detectable association between BMI category and the selected early outcomes. However, the confidence intervals did not establish equivalence, and the findings apply only to selected robotic surgical candidates.