Right Ventricular-Arterial Coupling Ratio Derived From 3-Dimensional Echocardiography Predicts Outcomes in Pediatric Pulmonary Hypertension

BACKGROUND: Right ventricular (RV) function is an important determinant of outcomes in pulmonary hypertension (PH). RV-arterial coupling ratio using stroke volume (SV) to end-systolic volume (ESV) has been shown to be an independent predictor of outcome in adults with PH. SV/ESV has not been used in pediatrics to predict outcomes. We compared SV/ESV between pediatric patients with PH, controls, and among groups based on disease severity. We correlated SV/ESV to RV strain and evaluated SV/ESV as a predictor of outcomes in pediatric PH. METHODS: One hundred and twenty-five children with PH (8 years [3-12 years]) underwent 3-dimensional echocardiography from 2014 to 2017 and compared with 65 controls (9 years [7-13 years]). Offline analysis generated 3-dimensional end-diastolic volume, ESV, SV, and free-wall RV longitudinal strain. SV/ESV ratios were compared between patients with PH, controls, and disease severity. Correlations between SV/ESV to free-wall RV longitudinal strain were assessed using general linear mixed models. Cox proportional hazards analysis assessed the predictive ability of SV/ESV. RESULTS: Patients with PH had lower SV/ESV compared with controls (0.88±0.18 versus 1.24±0.23; P<0.0001). There were significant associations between SV/ESV to free-wall RV longitudinal strain (r=-0.53; P<0.001). SV/ESV emerged as a strong predictor of adverse clinical event (hazard ratio [CI], 0.52 [0.38-0.69] per 0.1 increase in SV/ESV; P<0.0001). CONCLUSIONS: SV/ESV as a volume estimate of RV-arterial coupling ratio correlates with RV strain and is a strong predictor of adverse clinical events in pediatric PH.