Evaluation of the myocardial performance index and tissue doppler imaging by comparison to near-simultaneous catheter measurements in pediatric cardiac transplant patients.

BACKGROUND: Parameters derived from Doppler echocardiography, such as the myocardial performance index (MPI) and the ratio of peak velocity of early diastolic prograde flow (E) across the atrioventricular valve (AVV) divided by the peak velocity of early diastolic tissue motion at the AVV annulus (E') (E:E' ratio), are routinely used to assess ventricular function. However, they have not been compared with measurements obtained by cardiac catheterization (CC) in children.

METHODS: We prospectively studied post-cardiac transplant children undergoing CC with near-simultaneous echocardiographic imaging for MPI and E:E'. CC data included right atrial pressure (RAp), pulmonary artery wedge pressure (PAWp) and cardiac index (CI). One investigator, who was blinded to the CC data, measured right ventricular (RV) and left ventricular (LV) MPI and E:E' offline. Correlations between echocardiographic and catheter measurements were calculated. Receiver-operating-characteristics (ROC) curves were created to evaluate the utility of echocardiographic measurements that exhibited statistically significant correlations with CC measurements.

RESULTS: Twenty-four patients (age range 0.8 to 21 years) underwent 142 CCs during the study period. Of the 12 correlations studied, 3 met statistical significance (p < 0.05) (RV E:E' vs RAp, RV E:E' vs PAWp and LV MPI vs CI). The ROC areas for these correlations were 0.38, 0.42 and 0.68, respectively. There were no cut-off points where both the sensitivity and specificity for any measurement were >0.80.

CONCLUSIONS: Our data suggest that MPI and E:E' are poor predictors of simultaneously obtained, catheter-derived hemodynamic parameters in post-transplant children. These limitations should be carefully considered before ascribing diagnostic value to these measurements.