Discordant Grading of Aortic Stenosis Severity: Echocardiographic Predictors of Survival Benefit Associated With Aortic Valve Replacement

Abstract

Objectives: This study sought to assess the survival benefit associated with aortic valve replacement (AVR) according to different strata of echocardiographic parameters of aortic stenosis (AS) severity, and especially in patients with an aortic valve area (AVA) comprised between 0.8 cm(2) and 1 cm(2).

Background: Discordant findings between AVA (≤1.0 cm(2)) and mean gradient (MG) (<40 mm Hg) raise uncertainty regarding the actual severity of AS. Some studies suggested that the AVA threshold value to define severe AS should be decreased to 0.8 cm(2) to reconcile these discordances.

Methods: A total of 1,710 patients with documented moderate to severe AS by Doppler echocardiography were separated into 4 strata of AS severity based alternatively on AVA, indexed AVA, MG, or peak aortic jet velocity (Vpeak). We compared the survival rates of medically versus surgically treated patients. To eliminate covariate differences that may lead to biased estimates of treatment effect, a propensity matching with a greedy 5-to-1 digit-matching algorithm was used.

Results: Mean AVA was 0.9 ± 0.3 cm(2), mean MG 33 ± 18 mm Hg, and mean Vpeak 3.6 ± 0.9 m/s. A total of 1,030 (60%) patients underwent AVR within 3 months following echocardiographic evaluation. During a mean follow-up of 4.4 ± 3.0 years there were 469 deaths. Patients with an AVA between 0.8 cm(2) and 1.0 cm(2) had a significant observed survival benefit with AVR (hazard ratio: 0.37 [95% confidence interval: 0.21 to 0.63]; p = 0.0002). AVR was also associated with improved survival in patients with MG between 25 mm Hg and 40 mm Hg or Vpeak between 3 m/s and 4 m/s, but only in patients with concomitant AVA ≤1 cm(2) (p = 0.001 vs. p = 0.46 in patients with AVA >1 cm(2)).

Conclusions: These results do not support decreasing the AVA threshold value for severity to 0.8 cm(2) and they confirm that AVR is associated with improved survival in a substantial number of patients with discordant aortic grading.

Keywords: Doppler echocardiography; aortic valve stenosis; surgery; survival; valvular heart disease.