Efficacy of transcatheter low-dose thrombolysis in patients with intermediate-high risk pulmonary embolism. Study rationale and design

Aim. Comparison of conservative and invasive treatment strategies in patients with intermediate-high risk pulmonary embolism (PE) based on a multimodal assessment of efficacy and safety. Material and methods. This single-center, open-label, randomized, comparative trial will include 100 patients with a verified diagnosis of PE with intermediate-high risk of 30-day mortality. Patients will be randomized 1:1 to standard anticoagulant therapy or selective low-dose alteplase transcatheter thrombolysis. Patients will be followed for 12 months. The primary endpoint is a decrease in the right ventricle to left ventricle ratio by 20% or more from baseline at 48±6 hours after initiation of therapy. There are secondary endpoints: patient hemodynamic instability; ISTH major bleeding; Qanadli index decrease at 48 hours; degree of residual thrombosis with reduced perfusion at 3-6 months; incidence of post-thromboembolic syndrome at 3-6 months; 30-day, 90-day, and 1-year mortality. Conclusion. The study will provide important clinical data on the short- and long-term efficacy and safety of different treatment approaches in patients with intermediate-to-high-risk acute pulmonary embolism.