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

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)/cm² for women and 467 AU/cm² 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/cm² for women and 500 AU/cm² for men seem to be appropriate to identify severe AS. Further studies are needed to validate these thresholds, especially in diverse populations.