Multi-center Randomized Controlled Trial of Catheter-Directed Mechanical Thrombectomy Versus Systemic Thrombolysis in Patients with Acute Intermediate-to-High-Risk Pulmonary Embolism: Study Protocol.

PURPOSE: This study aims to compare the efficacy and safety of catheter-directed mechanical thrombectomy using the Tendvia system versus systemic thrombolysis in patients with intermediate-to-high-risk acute pulmonary embolism. MATERIALS AND METHODS: This is a 1:1 block-randomized, controlled, open-label parallel-group, multi-center, superiority trial. Eligible patients aged 18-75 years, diagnosed with intermediate-to-high-risk acute pulmonary embolism and hemodynamic deterioration, will be included. The main exclusion criteria are unsuitable target vessel criteria; sustained systolic hypotension; severe pulmonary hypertension; hematocrit < 28%; chronic pulmonary hypertension; left bundle branch block; chronic left heart failure; renal dysfunction; coagulopathy; recent cardiothoracic surgery; intracardiac thrombus. The intervention group will undergo catheter-directed thrombectomy using the Tendvia system under fluoroscopic guidance within 4 h of computed tomography pulmonary angiography. The control group will receive standard alteplase infusion. The primary efficacy endpoint is absolute reduction in the right ventricular/left ventricular diameter ratio from baseline to 48 h post-intervention, measured by blinded core-lab computed tomography pulmonary angiography analysis. The primary safety endpoint is the rate of composite major adverse events within 48 h. Secondary endpoints include the proportion of patients achieving a ≥ 50% reduction from baseline in NT-proBNP level at 48 h post-intervention, dyspnea scores, change in pulmonary arterial pressure, 48-h post-procedure clinical deterioration, symptomatic recurrence within 30 days, major access site complications, device-related serious adverse events, length of post-procedure hospital and intensive care unit stay, and change in cardiac biomarkers. EXPECTED GAIN OF KNOWLEDGE: This trial will provide evidence regarding the use of catheter-directed thrombectomy in intermediate-to-high-risk pulmonary embolism. TRIAL REGISTRATION: This study was registered in Clinicaltrials.gov on 2025-06-22 (Registration number NCT07032025).