The obesity paradox: association of obesity with improved survival in medically managed severe aortic stenosis

Abstract

INTRODUCTION The obesity paradox, where obesity is associated with improved survival, has been described in patients undergoing haemodialysis and in those with heart failure. It was also demonstrated in patients undergoing valve replacement for aortic stenosis (AS). We explored this phenomenon in medically managed severe AS. METHODS 154 patients with medically managed severe AS (aortic valve area index [AVAi] < 0.6 cm2/m2; mean pressure gradient > 40 mmHg and peak velocity > 400 cm/s) and preserved left ventricular ejection fraction (> 50%) were categorised into the obese (body mass index [BMI] Asian cut-off ≥ 27.5 kg/m2) and non-obese groups. Their clinical and echocardiographic profiles were compared. RESULTS 24 (15.6%) patients were obese. Obese patients were similar to non-obese patients in age (68.5 ± 11.6 years vs. 68.9 ± 13.1 years) but had higher prevalence of cardiovascular risk factors. Left atrial diameter (43.7 ± 6.7 mm vs. 38.5 ± 10.2 mm) was larger in obese patients, while left ventricular outflow tract diameter (19.5 ± 1.7 mm vs. 20.4 ± 2.1 mm) was smaller. Despite lower AVAi in obese patients (0.36 ± 0.10 cm2/m2 vs. 0.43 ± 0.11 cm2/m2), there was lower mortality (37.5% vs. 41.0%, log-rank 4.06, p = 0.045) on follow-up (8.0 ± 5.7 years). After adjusting for age and AVAi, higher BMI ≥ 27.5 kg/m2 remained protective for mortality (hazard ratio 0.38, 95% confidence interval 0.15 to 0.98, p = 0.046). CONCLUSION We demonstrated that obesity was associated with improved survival in severe AS despite lower AVAi and increased prevalence of cardiovascular risk factors.