Association of body mass index and outcomes in surgical and transcatheter aortic valve replacement

Background: The association between body mass index (BMI) and outcomes in surgical aortic valve replacement (SAVR) and transcatheter aortic valve replacement (TAVR) is not well understood. This study assessed the nuanced relationship between BMI and clinical outcomes in a nationally representative cohort undergoing aortic valve replacement. Methods: Adult (≥18 years) admissions for elective SAVR or TAVR from the 2016-2021 National Inpatient Sample were analyzed. BMI was categorized as underweight (<20), ideal weight (20-30), obesity class I (30-34.9), class II (35-39.9), and class III (≥40). The primary outcome was in-hospital mortality. Secondary outcomes included major adverse events (MAE), a composite of mortality and complications (e.g., stroke, thromboembolic, cardiac, respiratory, infection, renal). Results: Among 103,000 patients, 61.2 % underwent TAVR. TAVR patients were older (76 vs. 64 years; p < 0.001) and more frequently underweight (3.1 % vs. 1.5 %; p < 0.001) compared to SAVR patients. In TAVR, BMI < 20 was associated with higher mortality (AOR 2.99, 95 % CI 1.16-7.74) and MAE (AOR 1.74, 95 % CI 1.30-2.34) compared to ideal BMI. Obesity did not increase the overall incidence of MAE in patients undergoing TAVR. In SAVR, mortality was not associated with BMI, but underweight (AOR 2.05, 95 % CI 1.33-3.15) and class III obesity (AOR 1.34, 95 % CI 1.09-1.65) were linked to higher MAE risk. Conclusions: Extremes of BMI results in poorer outcomes in SAVR and TAVR. Underweight patients had increased risks across both approaches, while severe obesity elevated MAE risk in SAVR. These findings underscore the need for tailored perioperative strategies and risk counseling.