Abstract 12138: Impact of Pressure Recovery on Doppler Estimates of Pressure Gradient across Aortic Valve in Infants and Children: Correlation of Doppler- and Catheter-Derived Indices for Isolated Valvar Aortic Stenosis
Introduction: In pts with valvar aortic stenosis (AS), Doppler-derived peak instantaneous (PIG) and mean (MG) gradients are used to assess severity. Discrepancies exist between these estimates and peak-to-peak gradient (PPG) measured at catheterization. Pressure recovery may be a source of this discrepancy, but has not been routinely used in pediatrics, likely because of lack of validation.
Hypothesis: PIG, corrected to account for pressure recovery (cPIG), will more accurately predict PPG than either PIG or MG in pts with AS.
Methods: Echos of pts with >20 mmHg PPG were retrospectively re-read by an observer blinded to PPG. All studies preceded catheterization by <6 months. PIG and MG were obtained from apical 5-chamber (AP) and supra-sternal notch (SSN) views. Using a validated equation, cPIGAP and cPIGSSN were calculated. All estimates were compared to PPG by Pearson and intra-class correlation (ICC). Receiver-operating characteristic (ROC) curve analysis tested the ability of each measure to discriminate a PPG>50 mmHg. Errors in the estimates were assessed by Bland-Altman analysis.
Results: 66 pts with a median age of 11.3 yrs (2 days - 26.7 yrs) met criteria. PIGAP, MGAP, and cPIGAP had much stronger correlations (rho = 0.89, 0.84, 0.89; p<0.0001; Figure) to PPG, compared to PIGSSN, MGSSN, and cPIGSSN (rho = 0.55, 0.6, 0.58; p<0.0001). ICC remained very strong only for PIGAP (0.85) and cPIGAP (0.88). Area under the ROC curve was highest for PIGAP, cPIGAP and MGAP (0.99, 0.98, and 0.91). PPG was overestimated by PIG and underestimated by MG, though this error was lower when cPIGAP was used. A cutpoint of cPIGAP ≥56 mmHg correctly identified those patients with PPG >50 mmHg with ≥90% sensitivity and specificity.
Conclusions: Doppler estimates from AP view more accurately predict PPG compared to SSN. cPIGAP provides the most accurate estimate, with similar ROC and less overestimation compared to PIG, and should be the non-invasive measure of choice in assessing AS in children.
- © 2011 by American Heart Association, Inc.