Some patients develop pulmonary hypertension (PH) in the first months of life.

Knowledge gaps remain on their characteristics and long-term outcome.

In total, 563 consecutive patients (mean follow-up 4-years) with mPAP>20mmHg between 1–12months of life were included and their history examined.

Age was mean (SD) 154 (95) days, mPAP 40 (14) mmHg, transpulmonary gradient 31 (14) mmHg, pulmonary vascular resistance index (PVRi) 4.4 (3.9) WU.m². Genetic disease was found in 122 (19%).

Most frequent indications for cath were PH on TTE (220, 39%), shunt calculation/closure (256, 45%), or suspected pulmonary veins anomaly (51, 9%).

Majority of patients (404, 72%) had an open shunt, 37 (6%) repaired CHD, 57 (10%) postcapillary PH and 66 (12%) normal cardiac anatomy but lung development disease (36/66), severe systemic disease (9/66), drug induced (16/66), or heritable (4/66) PH.

In open shunt patients PVRi was<3WU.m² in 99 (41%), 3–6 in 89 (37%),>6 in 52 (22%). Thirteen (3%) patients were considered not operable due to high PVRi (3/13), combined lung diseases (5/13), and/or severe chromosomal abnormalities (6/13). PH related to open shunt was protective for persistent PH at follow-up (P<0.001) and survival (P<0.001, Fig. 1).

Overall PH at follow-up was found in 84 (15%) and independent risk factors for persistence of PH were lung disease (P<0.001), arterial switch for TGA (P<0.008), PVRi>6WU.m² (P<0.001), idiopathic PH (P=0.009), and low pulmonary vein saturation (P=0.05).

Mortality was 10% and survival was significantly reduced in patients with concomitant lung disease (P=0.001, Fig. 2), normal cardiac anatomy (P=0.001), and cath for suspected PH at TTE (P=0.014).

Open shunt normally causes PH in early life, but hardly impacts operability and isolated open shunt rarely results in PH or reduced survival at follow-up. Patients with normal cardiac anatomy and lung disease have higher PH-related mortality and prevalence of PH at follow-up.