Antithrombotic Therapy Use in Children With Pulmonary Hypertension.

The role of antithrombotic therapy in pulmonary hypertension (PH) remains uncertain, with conflicting adult data and limited pediatric evidence. This study aimed to describe real-world antithrombotic use in pediatric PH utilizing Pediatric Pulmonary Hypertension Network (PPHNet) registry data and a survey of PPHNet centers. We analyzed data of 1,716 patients from the PPHNet registry (2014-2024), comparing characteristics of those who received aspirin or warfarin with those who did not. A survey on real-world antithrombotic use was also distributed to 12 North American PPHNet centers in 2023. Eighteen percent of subjects received aspirin and 7% received warfarin. Patients who received aspirin or warfarin were more likely to have idiopathic/heritable PH. Aspirin or warfarin-treated patients demonstrated higher-risk features as evidenced by use of PH-targeted triple therapy (aspirin vs. no aspirin: 22% vs. 9%, p < 0.01; warfarin vs. no warfarin: 31% vs. 10%; p < 0.01) and higher mortality over a median follow-up of 3.2 years (aspirin vs. no aspirin: 14% vs. 9%, p = 0.008; warfarin vs. no warfarin: 19% vs. 9%, p = 0.001). Center-specific aspirin and warfarin use varied widely. Survey data demonstrated general agreement that antithrombotic therapy was not indicated for patients at lowest risk and probably indicated for patients at highest risk, but management of intermediate-risk patients varied considerably. Antithrombotic therapy is used infrequently in pediatric PH and primarily reserved for high-risk patients, with significant variation across centers. These findings highlight the need for further research to define which patients may benefit and guide evidence-based practice.