Indexing aortic valve area by body surface area increases the prevalence of severe aortic stenosis

Abstract

Background To account for differences in body size in patients with aortic stenosis, aortic valve area (AVA) is divided by body surface area (BSA) to calculate indexed AVA (AVA index ). Cut-off values for severe stenosis are <1.0 cm 2 for AVA and <0.6 cm 2 /m 2 for AVA index . Objective To investigate the influence of indexation on the prevalence of severe aortic stenosis and on the predictive accuracy regarding clinical outcome. Methods Echocardiographic and anthropometric data from a retrospective cohort of 2843 patients with aortic stenosis ( jet velocity >2.5 m/s) and from 1525 patients prospectively followed in the simvastatin and ezetimibe in aortic stenosis (SEAS) trial were analysed. Results The prevalence of severe stenosis increased with the AVA index criterion compared to AVA from 71% to 80% in the retrospective cohort, and from 29% to 44% in SEAS (both p<0.001). Overall, the predictive accuracy for aortic valve events was virtually identical for AVA and AVA index in the SEAS population (mean follow-up of 46 months; area under the receiver operating characteristic curve: 0.67 (95% CI 0.64 to 0.70) vs 0.68 (CI 0.65 to 0.71) (NS). However, 213 patients additionally categorised as severe by AVA index experienced significantly less valve related events than those fulfilling only the AVA criterion ( p<0.001). Conclusions Indexing AVA by BSA (AVA index ) significantly increases the prevalence of patients with criteria for severe stenosis by including patients with a milder degree of the disease without improving the predictive accuracy for aortic valve related events.

Outcome Implication of Aortic Valve Area Normalized to Body Size in Asymptomatic Aortic Stenosis

“…6,23 Although contemporary outcome data supporting the prognostic value of AVA/BSA are scant, 9,24 US and European guidelines 1,2 have included AVA/BSA among criteria for grading AS severity (ie, AVA/BSA <0.6 cm 2 /m 2 ). In a study including 103 asymptomatic patients with, AS, AVA/BSA 24 Jander et al 9 have recently shown that among patients with AS the number of patients with AVA/BSA <0.6 cm 2 /m 2 is significantly greater than the number of patients with AVA <1 cm 2 and that the predictive accuracy for aortic valve events of the 2 parameters is almost identical. 9 Our results show that asymptomatic patients with AS in whom at the time of diagnosis AVA/BSA is <0.4 cm 2 /m 2 represent a high-risk group with >60% rate of events at 2 years.…”

“…In a study including 103 asymptomatic patients with, AS, AVA/BSA 24 Jander et al 9 have recently shown that among patients with AS the number of patients with AVA/BSA <0.6 cm 2 /m 2 is significantly greater than the number of patients with AVA <1 cm 2 and that the predictive accuracy for aortic valve events of the 2 parameters is almost identical. 9 Our results show that asymptomatic patients with AS in whom at the time of diagnosis AVA/BSA is <0.4 cm 2 /m 2 represent a high-risk group with >60% rate of events at 2 years. We also clearly demonstrate that in asymptomatic AS, the use of higher AVA/BSA cutoffs result in similar risk of events during follow-up.…”

“…Recently, in the SEAS (Simvastatin and Ezetimibe in Aortic Stenosis) population, it has been shown that the use of the 0.6 cm 2 /m 2 cutoff increases by ≈10% the frequency of severe AS compared with the 1 cm 2 AVA cutoff. 9 It has also been suggested that a lower AVA/BSA cutoff might reduce grading inconsistencies and improve event prediction.…”

Ultrasound Imaging of Calcific Aortic Valve Disease

“…Indexing the valve area may reclassify smaller individuals from severe to moderate aortic stenosis (AS), but indexing all patients, particularly with extreme obesity, can lead to substantial overestimation of severity and should not be relied upon [ 18 ].…”

Update on Cardiac Imaging Techniques 2014

“…23 There are concerns about indexing aortic valve area by body surface area, as this system increases the prevalence of severe aortic stenosis cases by including patients with less advanced disease, without improving the diagnostic accuracy for valvular disease-related events. 24 This is especially important in obese patients because indexing by body surface area could clearly overestimate the severity of aortic valve stenosis. 25 A new score to predict the outcome of mitral valvuloplasty that incorporates mitral valve area 1 cm 2 , maximum leaflet displacement at diastole 12 mm, commissural area ratio 1.25, and subvalvular involvement has been validated in a large patient sample and has shown better predictive capacity than the Wilkins score.…”