Feasibility and safety of a standardized low-dose thrombolytic therapy for right-sided mechanical prosthetic valve thrombosis in adult congenital heart disease

Background: Mechanical valve thrombosis is a serious complication in adults with congenital heart disease (ACHD). Although low-dose thrombolytic therapy has emerged as a potential alternative to surgery, evidence in ACHD patients with right-sided mechanical valve thrombosis remains limited. We evaluated the feasibility and safety of a standardized low-dose thrombolytic protocol in this population. Methods: We retrospectively reviewed consecutive ACHD patients with right-sided mechanical valve thrombosis treated at our institution between 2022 and 2025. Diagnosis was based on fluoroscopic, echocardiographic, and computed tomography findings. All patients received a standardized low-dose alteplase regimen (25 mg over 6 h). Treatment efficacy was assessed primarily by restoration of prosthetic leaflet mobility on fluoroscopy. Results: Five patients were included: four with mechanical pulmonary valves and one with a mechanical tricuspid valve. Thrombosis occurred a median of 2.3 years after valve replacement, and all patients had subtherapeutic anticoagulation (international normalized ratio <2.0) during the preceding month. At presentation, four patients were in New York Heart Association functional class II and one in class III. Following a median of 5 days of thrombolytic therapy, complete restoration of prosthetic leaflet mobility was achieved in all patients. No major bleeding or thromboembolic complications occurred. During a median follow-up of 0.7 years, no recurrent valve thrombosis was observed. Conclusions: Standardized low-dose thrombolytic therapy was safe and feasible in this case series and may provide a non-surgical treatment option for ACHD patients with right-sided mechanical valve thrombosis.