Randomized Controlled Trial of Mechanical Thrombectomy With Anticoagulation Versus Anticoagulation Alone for Acute Intermediate-High Risk Pulmonary Embolism: Primary Outcomes From the STORM-PE Trial

BACKGROUND: Patients with intermediate-high risk pulmonary embolism (PE) have an elevated right ventricular (RV) to left ventricular (LV) diameter ratio and are at risk of early clinical decompensation and mortality. Reperfusion therapy aims to rapidly relieve acute RV pressure overload and to normalize hemodynamics. STORM-PE (A Prospective, Multicenter, Randomized Controlled Trial Evaluating Anticoagulation Alone Versus Anticoagulation Plus Mechanical Aspiration With the Indigo Aspiration System for the Treatment of Intermediate-High Risk Acute Pulmonary Embolism) is the first reported randomized controlled trial to test the efficacy and to evaluate the safety of mechanical thrombectomy, specifically computer-assisted vacuum thrombectomy (CAVT) with anticoagulation compared to anticoagulation alone. METHODS: STORM-PE is an international randomized controlled trial with 1:1 randomization to CAVT with anticoagulation or anticoagulation alone. Eligible adults had acute-onset (symptoms ≤14 days), intermediate-high risk PE and were normotensive, with an RV/LV ratio ≥1.0 on computed tomographic pulmonary angiography and elevated cardiac biomarkers. The primary end-point analysis tested for a difference between groups for the change in RV/LV ratio at 48 hours, assessed by a blinded independent imaging core laboratory. Secondary end points included major adverse events within 7 days (a composite of clinical deterioration necessitating rescue therapy, PE-related mortality, symptomatic recurrent PE, and major bleeding), adjudicated by an external clinical events committee. Additional outcomes included change in vital signs and core laboratory–assessed pulmonary artery obstruction at 48 hours. RESULTS: A total of 100 patients enrolled across 22 sites were randomized to CAVT (n=47) or anticoagulation alone (n=53). Baseline characteristics were comparable between arms. At 48 hours, mean reduction in RV/LV ratio was greater for CAVT (0.52±0.37) than anticoagulation (0.24±0.40), a difference of 0.27 (95% CI, 0.12–0.43; P <0.001). Refined modified and modified Miller scores exhibited greater changes for CAVT than anticoagulation alone at 48 hours ( P <0.001). Early normalization of vital signs within 48 hours was more frequent after CAVT. The major adverse event rate within 7 days was not different between groups (CAVT, 4.3% versus anticoagulation, 7.5%; P =0.681). Two PE-related deaths occurred in the CAVT arm. CONCLUSIONS: CAVT was superior to anticoagulation alone in reducing RV/LV ratio within 48 hours in patients with intermediate-high risk PE, accompanied by earlier normalization of vital signs and major adverse event rates comparable to those for anticoagulation. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT05684796.