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

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.