Thrombocytopenia Following Transcatheter Self-Expanding Pulmonary Valve Replacement.

Thrombocytopenia following transcatheter aortic valve implantation has been described, but platelet count decline after self-expanding transcatheter pulmonary valve replacement (TPVR) has not been previously highlighted. This study aimed to describe the frequency, magnitude, and short-term clinical associations of platelet count decline after self-expanding TPVR. We retrospectively reviewed all consecutive self-expanding TPVRs performed at our institution between May 2022 and August 2025. Demographic, procedural, echocardiographic, and laboratory data were collected, including platelet and hemoglobin levels before and after TPVR. Descriptive statistics were used, and correlation analysis assessed the relationship between platelet and hemoglobin decreases. Forty-one patients were included, with a median age of 18.7 years [IQR 16.1-23.9]; 80% had undergone tetralogy of Fallot repair. Twenty-one patients received a Harmony valve and 20 received an Alterra-Sapien valve. Pre- and post-procedural platelet counts were available in 30 patients. A platelet count decrease occurred in 27/30 patients (90%), including 23/30 (77%) with a decrease of > 25% or ≥ 50 × 10⁹/L. Platelet count fell below 150 × 10⁹/L in 14 patients (47%) and below 100 × 10⁹/L in five (17%). No bleeding or thrombotic complications were observed, and no patient required platelet transfusion or thrombocytopenia-directed intervention. Hemoglobin decrease was less common and did not correlate with platelet count decrease. No difference was observed between valve types. Early platelet count decline was frequent after self-expanding TPVR, with nearly half developing thrombocytopenia. Routine post-procedural platelet monitoring may be warranted.