RV stroke work in children with pulmonary arterial hypertension: estimation based on invasive haemodynamic assessment and correlation with outcomes.

BACKGROUND: RV performance is an important determinant of outcomes in children with pulmonary arterial hypertension (PAH). RV stroke work (RVSW), the product of mean pulmonary artery pressure and stroke volume, integrates contractility, afterload and ventricular-vascular coupling. RVSW has not been evaluated in children with PAH. We tested the hypothesis that RVSW would be a predictor of outcomes in children with PAH.

METHODS: Patients in the Children's Hospital Colorado PAH database were evaluated retrospectively, and those with idiopathic PAH and those with minor or repaired congenital heart disease were included. Haemodynamic data were obtained by catheterisation and echocardiography, performed within 3 months. RVSW was calculated: mean pulmonary arterial pressure × stroke volume, and indexed to body surface area. Statistics included Kruskal-Wallis, Wilcoxon rank sum, and Spearman correlation.

RESULTS: Fifty patients were included. Median age of the cohort was 9.5 (6.0, 15.7) years, with a median indexed pulmonary vascular resistance (PVRi) of 6.5 (3.7, 11.6) WU m(2). RVSW had a significant association with PVRi (r=0.6, p<0.0001), tricuspid annular systolic plane excursion (r=0.55, p=0.0001), and RV fractional area change (r=-0.4, p=0.005). Grouped by WHO class, there was a significant difference in RVSW (p=0.04). Need for atrial septostomy and death were associated with higher RVSW (p=0.04 and p=0.03, respectively).

CONCLUSIONS: RVSW can be estimated in children with PAH, and is significantly associated with abnormal WHO class, the need for septostomy, as well as mortality. Indices accounting for RV performance as well as ventricular-vascular coupling may be useful in the prognosis and, hence, management of children with PAH.