Relationship of Body Mass Index With Outcomes After Transcatheter Aortic Valve Replacement: Results From the National Cardiovascular Data–STS/ACC TVT Registry

Abstract

Objective: To investigate the relationship of body mass index (BMI) with short- and long-term outcomes after transcatheter aortic valve replacement (TAVR). Patients and Methods: The relationship between BMI and baseline characteristics and procedural characteristics was assessed for 31,929 patients who underwent TAVR between November 1, 2011, and March 31, 2015, from the STS/ACC TVT Registry. Registry data on 20,429 patients were linked to the Centers for Medicare and Medicaid Services to assess the association of BMI with 30-day and 1-year mortality using multivariable Cox proportional hazards models. The effect of BMI on mortality was also assessed with BMI as a continuous variable. Restricted cubic regression splines were used to model the effect of BMI and to determine appropriate cut points of BMI. Results: Among 31,929 patients, 806 (2.5%) were underweight (BMI, <18.5 kg/m2), 10,755 (33.7%) had normal weight (BMI, 18.5- 24.9 kg/m2), 10,691 (33.5%) were overweight (BMI, 25.0-29.9 kg/m2), 5582 (17.5%) had class I obesity (BMI, 30.0-34.9 kg/m2), 2363 (7.4%) had class II obesity (BMI, 35.0-39.9 kg/m2), and 1732 (5.4%) had class III obesity (BMI, ≥40 kg/m2). Patients in various BMI categories were different in most baseline and procedural characteristics. On multivariable analysis, compared with normal-weight patients, underweight patients had higher mortality at 30 days and at 1 year after TAVR (hazard ratio [HR], 1.35; 95% CI, 1.02-1.78 and HR, 1.41; 95% CI, 1.17-1.69, respectively), whereas overweight patients and those with class I and II obesity had a decreased risk of mortality at 1 year (HR, 0.88; 95% CI, 0.81-0.95, HR, 0.80; 95% CI, 0.72-0.89, and HR, 0.84; 95% CI, 0.72-0.98, respectively). For BMI of 30 kg/m2 or less, each 1-kg/m2 increase was associated with a 2% and 4% decrease in the risk of 30-day and 1-year mortality, respectively; for BMI greater than 30 kg/m2, a 1-kg/m2 increase was associated with a 3% increased risk of 30-day mortality but not with 1-year mortality. Conclusion: Results of this large registry study evaluating the relationship of BMI and outcomes after TAVR support the existence of an obesity paradox among patients with severe aortic stenosis undergoing TAVR.