Impact of obesity and nonobesity on grading the severity of aortic valve stenosis

Abstract

We tested the hypothesis that the disproportionate increase of body surface area in obesity may lead to the overestimation of aortic stenosis (AS) severity when the aortic valve area (AVA) is indexed (AVAI) for body surface area in 1,524 patients enrolled in the Simvastatin and Ezetimibe in AS study. Obesity was defined as a body mass index of ≥30 kg/m(2). Peak aortic jet velocity, mean aortic gradient, AVA, and energy loss (EL) did not differ, although AVAI and EL indexed (ELI) for body surface area were significantly smaller in the obese group (n = 321) compared with the nonobese (n = 1,203) group (both p <0.05). Severe AS by AVAI (<0.6 cm(2)/m(2)) but nonsevere by AVA (>1.0 cm(2); AVAI/AVA discordance) was found in 15% of the patients, whereas severe AS by ELI (<0.6 cm(2)/m(2)) but nonsevere by EL (>1.0 cm(2); ELI/EL discordance) was found in 9% of the patients. Obesity was associated with a 2.4-fold higher prevalence of AVAI/AVA discordance and a 1.6-fold higher prevalence of ELI/EL discordance. Discordant grading was also associated with male gender, larger body size, higher mean aortic gradient, and stroke volume (all p <0.05). During a median follow-up of 4.3 years, 419 patients were referred for aortic valve replacement and 177 patients died or were hospitalized because of heart failure. In the Cox regression analyses, AVAI/AVA discordance was associated with a 28% higher rate of aortic valve replacement (p <0.05) but did not predict the rate of combined death and hospitalization for heart failure. In conclusion, using AVAI and ELI for the grading of stenosis in patients with obesity may lead to overestimation of true AS severity.