Ultraslow low-dose thrombolytic therapy in patients with acute mechanical prosthetic heart valve thrombosis – A prospective cohort study

Background: While surgery still remains the gold standard treatment for mechanical prosthetic valve thrombosis (MPVT) by many guidelines, the ultraslow low-dose thrombolytic regimen has been reported as a promising alternative. Methods: In this prospective single-center cohort, patients with acute MPVT were treated with an ultraslow low-dose thrombolytic regimen consisting of 25 mg infusion of recombinant tissue-type plasminogen activator (rtPA) over 25 h. The regimen could be repeated in case of failure until resolution/occurrence of adverse events or a maximum cumulative dose of 150 mg. The primary outcome was the complete MPVT resolution rate; other outcomes included first-dose success rate, major bleeding, thromboembolic events, mortality, and total thrombolytic dose/duration. Results: Between April 2018 to January 2024, 135 episodes of acute MPVT were treated with an ultraslow low-dose thrombolytic regimen in 118 patients. In 118/135 (87.4 %) episodes, right-sided prosthetic valve was involved. Complete success was achieved in 88.1 % of cases, with 39.5 % responding after the first dose. The median total dose was 50 mg over a median of 30 h. Only one fatal intracranial hemorrhage occurred (0.7 %), with no other bleeding or thromboembolic complications. Conclusion: The ultraslow low-dose thrombolytic regimen appears to exhibit high efficacy and acceptable safety in treating acute MPVT. Further large clinical trials are essential for validating these preliminary findings.