Abstract 16546: Right Ventricular Systolic Function Assessed by Real Time 3-Dimensional Echocardiography Correlates with Invasive Cardiac Output, and Predicts Functional Status in Patients with Pulmonary Hypertension

Abstract

Background: Right ventricular systolic function (RVSF) is a critical determinant of outcome in patients with pulmonary hypertension (PH). Longitudinal studies to evaluate efficacy of PH therapy are hampered by the limited accuracy and reproducibility of 2D echocardiographic methods for RVSF quantitation. Real Time 3-Dimensional Echocardiography (RT3DE) avoids geometric assumptions about RV shape, but its accuracy and prognostic power have not been tested extensively in patients with PH. Hypothesis: RT3DE measurements of RVSF are accurate and correlate with functional outcomes in patients with PH.

Methods and Results: Validation Study: RT3DE-derived RV and LV stroke volume (SV) measurements were obtained soon (5 - 10 min.) after invasive thermodilution (TD) measurements in 15 adult patients (Pts) with hemodynamically confirmed PH (Mean Pulmonary artery pressure ≥ 25 mm Hg), without any significant valvular regurgitation. We found that RT3DE RVSV correlated strongly with TD SV (range: 49 - 201 ml, r=0.92, SE = 5 ml). We also found that RT3DE LVSV correlated strongly with TD SV (r = 0.87, SE = 6 ml), and with RT3DE RVSV (r = 0.93, SE = 3 ml). Longitudinal Follow-up Study: Subsequently, we performed RT3DE before and after 9 + 1 (mean ± SE) months of follow-up in 16 pts with WHO Group I PH, and correlated findings with Pt. functional class (FC). Symptoms improved by > 1 WHO FC, in 3/16 Pts. and was associated with a +9 ± 1% improvement in RT3DE RV ejection fraction (EF), whereas RVEF changed by only +4 ± 2% in pts whose symptoms did not improve (p = 0.02). There was modest significant correlation between RVSV and RVEF and Borg dyspnea scores (r= -0.54; p=0.004 and r= -0.6; p=0.001 respectively) and Borg exertion scores (r= -0.6; p=0.001 and r= -0.5; p=0.002 respectively).

Conclusions: In Pts. with PH, RT3DE measures of RVSV and LVSV correlate strongly with invasive thermodilution measurements. Because RT3DE SV measurements are predicated on end-diastolic and end-systolic volumes, RVEF and LVEF can also be reported with confidence. In a small preliminary series, RT3DE findings correlate modestly with functional outcomes in Pts. with PH. Larger studies are needed to determine whether RT3DE can be useful for evaluation of the efficacy of therapeutic interventions for Pts. with PH.