Right ventricular to left ventricular diameter ratio at end-systole in evaluating outcomes in children with pulmonary hypertension

Background: Pulmonary hypertension (PH) increases right ventricular (RV) pressure, resulting in septal shift and RV dilation. Few echocardiographic measures have been used to evaluate severity and outcomes in children with PH. The aims of this study were to compare the RV to left ventricular (LV) diameter ratio at end-systole (RV/LV ratio) in normal controls and patients with PH, to correlate the RV/LV ratio with invasive hemodynamic measures, and to evaluate its association with outcomes in children with PH.

Methods: The RV/LV ratio was compared retrospectively between 80 matched normal controls and 84 PH patients without shunts. Of the patients with PH, 49 children underwent 94 echocardiographic studies and cardiac catheterizations within 48 hours (13 patients had simultaneous measurements). The RV/LV ratio was correlated against hemodynamic measures. Kaplan-Meier curves and a Cox proportional-hazards regression model were used to assess relationships between RV/LV ratio and time until an adverse clinical event (initiation of intravenous prostacyclin therapy, atrial septostomy, death, or transplantation).

Results: RV/LV ratios were lower in controls compared with patients with PH (mean, 0.51 [95% confidence interval, 0.48-0.54] vs 1.47 [95% confidence interval, 1.25-1.70], P < .01). The RV/LV ratio correlated significantly with mean pulmonary artery pressure, systolic pulmonary artery pressure, systolic pulmonary artery pressure as a percentage of systemic pressure, and pulmonary vascular resistance index (r = 0.65 [P < .01], r = 0.6 [P < .01], r = 0.49 [P < .01], and r = 0.43 [P < .01], respectively). Twenty-two patients with PH with RV/LV ratios > 1 had adverse events within a median of 1.1 years from their earliest echocardiographic studies. Increasing RV/LV ratio was associated with an increasing hazard for a clinical event (hazard ratio, 2.49; 95% confidence interval, 1.92-3.24).

Conclusions: The RV/LV end-systolic diameter ratio can easily be obtained noninvasively in the clinical setting and can be used in the management of patients with PH. The RV/LV ratio incorporates both pathologic septal shift and RV dilation in children with PH and correlates with invasive measures of PH. An RV/LV ratio > 1 is associated with adverse clinical events.