<p>Pulmonary arterial hypertension causes significant morbidity and mortality in pediatric patients. Current guidelines speak about the need for new strategies to diagnose and monitor pulmonary hypertension in pediatrics. Digital subtraction pulmonary angiography is a useful tool to assess lung vasculature and parenchymal perfusion deficits. A Pulmonary Vascular Underperfusion Score has been previously published and used to assess pulmonary vasoreactivity testing response in premature infants with bronchopulmonary dysplasia and pulmonary hypertension. By adopting this Pulmonary Vascular Underperfusion Score, we performed a retrospective review for evaluating children with pulmonary arterial hypertension. Our study demonstrates that the Pulmonary Vascular Underperfusion Score is strongly associated with pulmonary vascular resistance in pediatric patients with pulmonary arterial hypertension. Specifically, a score of ≥ 1.5 reliably identified patients with elevated pulmonary vascular resistance, both at baseline and during vasodilator testing, with high sensitivity and specificity. These findings suggest that Pulmonary Vascular Underperfusion Score may be a useful tool in risk stratification of children with pediatric pulmonary artery hypertension.</p>