(843) - Is Doppler Echocardiography Useful for Estimating Ventricular Filling Pressures in Pediatric Heart Transplant Recipients?

Abstract

Left ventricular (LV) E/E’ ratio - the ratio of mitral inflow and annular tissue Doppler imaging (TDI) velocities- is accepted as a surrogate for LV filling pressure in adults but has performed poorly in children. We hypothesized that transforming raw Doppler velocities into z-scores using pediatric normative data will improve the reliability of echocardiographic measures to estimate LV filling pressure in pediatric heart transplant (HT) recipients. All echocardiograms with TDI performed within 24 hours of a heart catheterization during 2005-2011 were identified (N=751 studies in 122 HT recipients, median 6/pt). Age-based normative values in 380 healthy children were used to transform biventricular inflow and TDI velocities into z-scores. Multivariable generalized estimating equation models - which account for multiple studies in individual patients - were developed to relate mitral inflow and TDI velocities to pulmonary capillary wedge pressure (PCWP). A similar analysis was performed for mean right atrial pressure (RAP) using right ventricular (RV) Doppler velocities. The median age of the study cohort at first evaluation was 13.9 yrs (IQR 6.4-16.8 yrs). The median duration between HT and the first study was 1.9 yrs (IQR 0.1-6.4 yrs). Although LV E/E’ ratio was associated with PCWP in univariate analysis (R2 =0.11, P<0.001), the final multivariable model for PCWP included mitral inflow E and LV S’ velocities (R2=0.17, P<0.001) but not LV E/E’ ratio.Using z-scores for mitral E and LV S’ velocities modestly improved the model for estimating PCWP (R2= 0.20, P<0.001) whereas LV E/E’ z-score ratio was not significant. A multivariable model for RAP included RV E’, RV A’ and septal A’ velocities (R2=0.11, P<0.001) but not RV E/E’ ratio. Transforming these velocities to z-scores did not strengthen the association. There is only a modest association between Doppler echocardiography velocities and PCWP (or RAP) in pediatric HT recipients which is not improved by using z-scores for LV E/E’ ratio or other velocities. Cardiac catheterization retains its value in pediatric HT recipients for accurate assessment of LV and RV filling pressures in clinical care.