Outcomes of Hypoattenuating Leaflet Thickening Post-Transcatheter Pulmonary Valve Replacement

BACKGROUND: Transcatheter pulmonary valve replacement (TPVR) is a mainstay of therapy for right ventricular outflow tract dysfunction, especially in adult congenital heart disease. OBJECTIVES: This study aimed to assess the prevalence, characteristics, and clinical implications of hypoattenuating leaflet thickening (HALT) and hypoattenuation affecting motion (HAM) after TPVR. METHODS: This was a retrospective cohort study of TPVR performed from 2018 to 2024. Computed tomography angiography (CTA) assessed for HALT/HAM and echocardiography assessed valve gradients. Random forests for survival were used to assess the association between the rate of change in echocardiographic gradient and the time-related likelihood of HALT. RESULTS: Of 106 patients with TPVR, 46 (39.6%) underwent CTA at 8.4 (6.1-24) (median [Q1-Q3]) months after TPVR. Twenty-six were in native right ventricular outflow tract, 12 were valve-in-valve, and 8 were in homografts. Eight patients (17.4%) had evidence of HALT ± HAM on CTA, 3 with valve deterioration. The median follow-up was 10 (2.4-23) months. No HALT/HAM was noted in patients on anticoagulation. Of the 5 with only HALT, one resolved, while one progressed. Three patients had HAM (6.5%), of which 2 had echocardiographic valve deterioration: one with mean gradient increase of 10 mm Hg, and one with ≥1-grade progression of regurgitation. All were treated with anticoagulation. CONCLUSIONS: In this series of patients with TPVR, there was a 17.4% prevalence of HALT and 6.5% prevalence of HAM, with evidence of echocardiographic valve deterioration. Increases in valve gradients were associated with a higher likelihood of HALT. This is critical in adult congenital heart disease patients, where valve longevity is essential to reduce repeated interventions.