Pulmonary Artery Pulsatility Index: A Novel Marker for Risk Assessment and Prognosis in Pediatric Idiopathic Pulmonary Arterial Hypertension.

The pulmonary artery pulsatility index (PAPi), calculated as (systolic pulmonary artery pressure - diastolic pulmonary artery pressure)/mean right atrial pressure). This study aimed to assess the clinical utility of PAPi in risk stratification for pediatric idiopathic pulmonary arterial hypertension (IPAH) and its performance in predicting the need for invasive intervention due to severe right heart failure. We analyzed clinical, echocardiographic, and right heart catheterization findings of 24 IPAH patients between April 2019 and November 2024. Statistical analyses included ROC curve analysis for PAPi's diagnostic performance, Kaplan-Meier survival analysis, and Cox regression for identifying independent predictors of intervention. The study included 24 patients (mean age 8.2 ± 4.7 years, 66.7% female). Based on pediatric risk classification, 45.8% were lower-risk, and 54.2% were high-risk, with PAPi significantly lower in high-risk patients (p < 0.001). ROC analysis identified PAPi < 3.24 as a strong predictor of high-risk status (sensitivity = 92%, specificity = 82%). PAPi correlated positively with 6MWT (r = 0.802) and TAPSE (r = 0.812) and negatively with WHO-FC (r =  - 0.692) and NT-proBNP (r =  - 0.713) (p < 0.001). Over 22 ± 15.9 months, 37.5% (n = 9) required invasive interventions for syncope, WHO-FC III/IV symptoms, or right ventricular failure, including atrial septostomy (77.8%), partial ASD closure (11.1%), and reverse Potts shunt (11.1%). Post-intervention, all but one patient improved. Patients requiring intervention had lower PAPi (1.88 ± 0.71 vs. 3.95 ± 1.27, p < 0.001). Kaplan-Meier analysis confirmed PAPi > 3.24 was associated with longer event-free survival (p = 0.002). Cox regression showed higher PAPi independently predicted lower intervention risk (HR 0.36, p = 0.042). In conclusion, this study suggests that PAPi is a reliable prognostic marker for risk stratification and predicting the need for invasive intervention in pediatric IPAH.