eComment. Obese aortic stenosis patients deserve special attention to prevent kidney injury

Aortic stenosis and renal failure are mainly diseases of elderly population. Both of them consume a disproportionate share of healthcare resources worldwide. Each causes severe morbidity and mortality by itself, yet their coexistence alters upside down the clinical course. Helgason et al. published survival data of patients who develop acute kidney injury (AKI) after aortic valve replacement (AVR) for aortic stenosis. AKI is a frequent (22.5%) complication of AVR. Authors defined transfusion of red blood cells, obesity and prolonged cardiopulmonary bypass time as independent risk factors for AKI [1]. According to recent studies obesity is a risk factor for renal failure even in healthy population. We want to underscore the possible contribution of obesity on renal failure in aortic stenosis patients. Even metabolically healthy overweight or obese individuals seem to be at higher risk for renal insufficiency. In a prospective cohort study, over 60 000 healthy individuals were stratified into underweight, normal weight, overweight and obese groups [2]. At baseline, all participants were free from renal insufficiency. Compared to those with normal weight, five-year cumulative incidence of renal insufficiency was higher among overweight or obese participants, with adjusted differences of 3.5 (95% CI 0.9-6.1) and 6.7 (95% CI 3.0-10.4) cases per 1000 respectively. The effect of obesity on eGFR increases with age, especially after age forty. According to another study even weight gain increases the risk for renal insufficiency if one remains within the "normal" category of body mass index [3]. In the light of present studies there is no doubt that obese aortic stenosis patients deserve special attention to prevent kidney injury especially after AVR. Chronic kidney disease may be under-recognized, which may contribute to the rising prevalence of end-stage renal disease. Screening of obese aortic stenosis patients even at early stages of the disease is crucial as renal insufficiency also increases the progression of stenosis. More than 1 in 5 AKI after AVR is a striking complication ratio. Physicians must be aware of kidney injury in obese AS patients. Risk modification with weight loss in early stages of aortic stenosis may prevent AKI after AVR and lengthen survival. Conflict of interest: none declared.