Size-adjusted aortic valve area: refining the definition of severe aortic stenosis

Aims Severe aortic valve stenosis (AS) is defined by an aortic valve area (AVA) <1 cm(2) or an AVA indexed to body surface area (BSA) <0.6cm/m(2), despite little evidence supporting the latter approach and important intrinsic limitations of BSA indexation. We hypothesized that AVA indexed to height (H) might be more applicable to a wide range of populations and body morphologies and might provide a better predictive accuracy. Methods and results In 1298 patients with degenerative AS and preserved ejection fraction from three different countries and continents (derivation cohort), we aimed to establish an AVA/H threshold that would be equivalent to 1.0 cm(2) for defining severe AS. In a distinct prospective validation cohort of 395 patients, we compared the predictive accuracy of AVA/BSA and AVA/H. Correlations between AVA and AVA/BSA or AVA/H were excellent (all R-2 > 0.79) but greater with AVA/H. Regressions lines were markedly different in obese and non-obese patients with AVA/BSA (P<0.0001) but almost identical with AVA/H (P=0.16). AVA/BSA values that corresponded to an AVA of 1.0 cm(2) were markedly different in obese and non-obese patients (0.48 and 0.59 cm(2)/m(2)) but not with AVA/H (0.61 cm(2)/m for both). Agreement for the diagnosis of severe AS (AVA<1 cm(2)) was significantly higher with AVA/H than with AVA/BSA (P<0.05). Similar results were observed across the three countries. An AVA/H cut-off value of 0.6 cm(2)/m [HR=8.2(5.6-12.1)] provided the best predictive value for the occurrence of AS-related events [absolute AVA of 1 cm(2): HR=7.3(5.0-10.7); AVA/BSA of 0.6 cm(2)/m(2) HR=6.7(4.4-10.0)]. Conclusion In a large multinational/multiracial cohort, AVA/H was better correlated with AVA than AVA/BSA and a cut-off value of 0.6 cm(2)/m provided a better diagnostic and prognostic value than 0.6 cm(2)/m(2). Our results suggest that severe AS should be defined as an AVA < 1 cm(2) or an AVA/H<0.6 cm(2)/m rather than a BSA-indexed value of 0.6 cm(2)/m(2).

Automated summary

This study found that aortic valve area indexed to height may be more accurate in defining severe AS compared to the indexed to body surface area. The results suggest that AVA/H is better correlated with AVA than AVA/BSA and may provide a better predictive accuracy for severe AS.