Does the body mass index predict mortality after isolated aortic valve replacement?

Data relating to the impact of body mass index (BMI) on outcomes after isolated aortic valve replacement (AVR) are scarce and controversial. The study aim was to investigate the predictive value of BMI for early and late mortality after isolated AVR.

Data obtained from patients who underwent isolated AVR between January 1998 and December 2010 at the authors' institution were analyzed retrospectively. Patients were allocated to five groups according to the preoperative BMI: underweight (BMI < 20 kg/m2); normal weight (BMI 20.0-24.9 kg/m2); overweight (BMI 25.0-29.9 kg/m2); obese (BMI 30.0-34.9 kg/m2); and morbidly obese (BMI > 34.9 kg/m2). Logistic and Cox regression analyses were performed to identify the independent predictors of early and late mortality, respectively.

After excluding 20 patients who were lost to follow up, and 30 patients with missing preoperative BMI data, a total of 1,758 patients was included in the analysis. The mean follow up was 5.6 +/- 3.5 years (range: 0-13.4 years), and the mean BMI 26.8 +/- 4.3 kg/m2 (range: 17-52 kg/m2). Multivariate logistic regression analyses showed no association between early mortality and the BMI groups. Multivariate Cox regression analyses showed 'underweight' to be an independent predictor for late mortality (hazard ratio 2.89; 95% confidence interval 1.63-5.13, p < 0.0001).

'Underweight' is an independent predictor for late mortality after AVR surgery. Morbid obesity did not prove to be predictive of a worse late survival.