BMI and acute kidney injury post transcatheter aortic valve replacement: unveiling the obesity paradox

Acute kidney injury (AKI) may complicate transcatheter aortic valve replacement (TAVR) leading to higher mortality. The relationship between AKI, obesity, and mortality, however, is controversial. We sought to investigate the impact of body habitus on the prognostic value of AKI in TAVR.

Among the 645 patients who underwent successful TAVR in a single high-volume centre, we retrospectively evaluated the association between AKI-TAVR and 30-day, 6-month, and 1-year mortality, and whether this relationship was affected by BMI. AKI was defined according to the Valve Academic Research Consortium-2 criteria. Patients were categorized into three groups by BMI: low-to-normal weight (<25 kg/m2), overweight (25-30 kg/m2), obese (>30.0 kg/m2).

Three-hundred and twenty-four (50.2%) patients were low-to-normal weight, 223 (34.6%) overweight, and 98 (15.2%) obese. AKI occurred in 141 (21.9%), similarly across BMI groups. Thirty-day, 6-month, and 1-year mortality rates were 2.2, 3.7, and 7.9%, without differences across BMI groups. Among patients who developed AKI-TAVR, 30-day (8.7 vs. 2.0 vs. 0.0%), 6-month (13.0 vs. 6.1 vs. 4.3%), and 1-year (20.3 vs. 12.2 vs. 4.3%) mortality showed a decreasing trend across increasing BMI categories (all P < 0.05); the same trend was not observed for patients without AKI-TAVR. In multivariate models, AKI was associated with 30-day [odds ratio (OR): 2.46, 95% confidence interval (CI): 1.70-8.67], 6-month (OR: 2.75, 95% CI: 1.32-7.59), and 1-year mortality (OR: 1.84, 95% CI: 1.22-3.71, all P < 0.05). The interaction between AKI and BMI, when added to the models, was consistently significant (all P < 0.05).

Higher BMI is associated with better survival in TAVR patients who develop AKI.