Weighing the risks: The impact of body mass index on postoperative complications in cardiac surgery.

Abstract

Introduction: Body mass index (BMI) is a key determinant of cardiovascular risk and may significantly impact postoperative outcomes. This study aimed to evaluate the relationship between BMI and early postoperative complications in patients undergoing cardiac surgery.

Methods: This retrospective study analyzed data from 555 patients who underwent cardiac surgery at the National Institute of Cardiology from June 2022 to December 2023. Patients were categorized into 4 BMI groups: underweight, normal weight, overweight, and obese. Data on demographics, surgical procedures, postoperative complications, and hemodynamic parameters were collected and analyzed.

Results: Preoperative comorbidities, including chronic heart failure and atrial fibrillation, were more common among underweight patients. This group was also at higher risk of postcardiotomy low output syndrome (univariate OR 3.35, p = 0.03), and postoperative atrial fibrillation remained significant in multivariate analysis (OR 1.48, p = 0.01), and required increased vasopressor and inotropic support. Obese patients had a significantly increased risk of postoperative mediastinitis in both univariate (OR 2.47, p = 0.04) and multivariate analyses (OR 2.12, p = 0.03). In-hospital mortality was 14.3 % in underweight vs. 6.1 % in obese patients (p = 0.52).

Conclusions: This study highlights the significant impact of BMI on postoperative outcomes in cardiac surgery. Underweight patients exhibited higher rates of postoperative complications and mortality, likely due to underlying comorbidities and limited physiological reserves. While obesity is associated with increased cardiovascular risk, our findings suggest a potential "obesity paradox" in this cohort. Further research is needed to elucidate the underlying mechanisms and refine risk stratification models incorporating BMI and other relevant factors.