Aortic Valve Calcification Density Measured by MDCT in the Assessment of Aortic Stenosis Severity

Abstract

BACKGROUND: Aortic valve calcification (AVC) indexation to the aortic annulus (AA) area measured by Doppler echocardiography (AVCd Echo ) provides powerful prognostic information in patients with aortic stenosis (AS). However, the indexation by AA measured by multidetector computed tomography (AVCd CT ) has never been evaluated. The aim of this study was to compare AVC, AVCd CT , and AVCd Echo with regard to hemodynamic correlations and clinical outcomes in patients with AS. METHODS: Data from 889 patients, mainly White, with calcific AS who underwent Doppler echocardiography and multidetector computed tomography within the same episode of care were retrospectively analyzed. AA was measured both by Doppler echocardiography and multidetector computed tomography. AVCd CT severity thresholds were established using receiver operating characteristic curve analyses in men and women separately. The primary end point was the occurrence of all-cause mortality. RESULTS: Correlations between gradient/velocity and AVCd were stronger (both P ≤0.005) using AVCd CT (r=0.68, P <0.001 and r=0.66, P <0.001) than AVC (r=0.61, P <0.001 and r=0.60, P <0.001) or AVCd Echo (r=0.61, P <0.001 and r=0.59, P <0.001). AVCd CT thresholds for the identification of severe AS were 334 Agatston units (AU)/cm 2 for women and 467 AU/cm 2 for men. On a median follow-up of 6.62 (6.19–9.69) years, AVCd CT ratio was superior to AVC ratio and AVCd Echo ratio to predict all-cause mortality in multivariate analyses (hazard ratio [HR], 1.59 [95% CI, 1.26–2.00]; P <0.001 versus HR, 1.53 [95% CI, 1.11–1.65]; P =0.003 versus HR, 1.27 [95% CI, 1.11–1.46]; P <0.001; all likelihood test P ≤0.004). AVCd CT ratio was superior to AVC ratio and AVCd Echo ratio to predict survival under medical treatment in multivariate analyses (HR, 1.80 [95% CI, 1.27–1.58]; P <0.001 compared with HR, 1.55 [95% CI, 1.13–2.10]; P =0.007; HR, 1.28 [95% CI, 1.03–1.57]; P =0.01; all likelihood test P <0.03). AVCd CT ratio predicts mortality in all subgroups of patients with AS. CONCLUSIONS: AVCd CT appears to be equivalent or superior to AVC and AVCd Echo to assess AS severity and predict all-cause mortality. Thus, it should be used to evaluate AS severity in patients with nonconclusive echocardiographic evaluations with or without low-flow status. AVCd CT thresholds of 300 AU/cm 2 for women and 500 AU/cm 2 for men seem to be appropriate to identify severe AS. Further studies are needed to validate these thresholds, especially in diverse populations.