Correction of Doppler Gradients for Pressure Recovery Improves Agreement with Subsequent Catheterization Gradients in Congenital Aortic Stenosis

Background: In congenital aortic stenosis (AS), suboptimal agreement between Doppler-derived gradients and catheterization gradients may lead to inappropriate referrals for catheterization. To address this problem, the authors investigated whether adjusting Doppler gradients for pressure recovery (PR) improved their agreement with subsequent catheterization gradients.

Methods: One hundred encounters in which patients with congenital AS underwent echocardiography and subsequent catheterization were retrospectively identified. Peak instantaneous and mean transaortic Doppler gradients were recorded from an apical view. PR (mm Hg) was calculated as 4VCW(2) × (2 × EOA/AOA) × (1 - EOA/AOA), where VCW is continuous-wave peak velocity, EOA is effective orifice area (stroke volume/velocity-time integral), and AOA is aortic cross-sectional area (π × radius(2)). The PR-corrected peak Doppler gradient was calculated as peak Doppler gradient - PR. Doppler gradients were tested for correlation and agreement with the peak-to-peak systolic gradient at catheterization (cath gradient).

Results: The median age was 12.9 years (range, 0.7-24.6 years). Median AS gradients were as follows: cath, 39 mm Hg (range, 0-103 mm Hg); peak Doppler, 48 mm Hg (range, 10-94 mm Hg); mean Doppler, 25 mm Hg (range, 4-58 mm Hg); and PR-corrected peak Doppler, 35 mm Hg (range, 5-78 mm Hg). Correlation coefficients between the various Doppler and cath gradients were not significantly different. The mean difference between Doppler and cath gradients was smallest for the PR-corrected peak Doppler gradient (-4.1 ± 14.1 mm Hg), followed by the uncorrected peak Doppler gradient (9.7 ± 15.9 mm Hg) and the mean Doppler gradient (-14.6 ± 15.6 mm Hg) (P < .001). Receiver operating characteristic curve analysis for a cath gradient ≥ 35 mm Hg revealed a significantly larger area under the curve for the PR-corrected peak Doppler gradient (0.85) compared with the uncorrected peak Doppler gradient (0.80) (P = .004) and the mean Doppler gradient (0.78) (P = .001). A PR-corrected peak Doppler gradient ≥ 27 mm Hg was associated with a cath gradient ≥ 35 mm Hg with 90% sensitivity and 61% specificity.

Conclusions: In congenital AS, correcting the peak Doppler gradient for PR significantly improved agreement with the subsequently measured cath gradient. This approach may improve decisions regarding referral for catheterization.