Tricuspid Nonbacterial Thrombotic Endocarditis in Antiphospholipid Syndrome with Chronic Thromboembolic Pulmonary Hypertension: A Case Report

Background Antiphospholipid syndrome (APS) can cause both pulmonary vascular and valvular complications, but the coexistence of chronic thromboembolic pulmonary hypertension (CTEPH) with right-sided nonbacterial thrombotic endocarditis (NBTE) is rare. This case illustrates the interaction between immune-mediated thrombosis, persistent pulmonary vascular obstruction, and acute valvular involvement. Case Presentation A 54-year-old man with longstanding, refractory CTEPH and recurrent hemoptysis underwent multiple balloon pulmonary angioplasty procedures and escalation to advanced pulmonary hypertension therapy. Following the switch from warfarin to apixaban, surveillance echocardiography revealed thickening of the tricuspid leaflet tips with an attached thrombotic mass. In the presence of negative blood cultures, these findings raised suspicion for NBTE. Rheumatologic evaluation confirmed triple-positive APS. Warfarin was reinstated, and immunosuppressive therapy with corticosteroids, hydroxychloroquine, and plasmapheresis was initiated, resulting in complete resolution of the vegetations and clinical stabilization over one year. Discussion APS should be considered in patients with early-onset or treatment-refractory CTEPH. New sterile valvular vegetations warrant immediate autoimmune evaluation. In high-risk APS, vitamin K antagonists remain the preferred anticoagulant, and combined anticoagulation and immunosuppression can achieve full valvular recovery.