Randomized controlled trial of mechanical thrombectomy with anticoagulation versus anticoagulation alone for acute intermediate-high risk PE: Primary outcome and functional endpoints from STORM-PE

Abstract Background Active removal of thrombus using mechanical thrombectomy (MT) in acute PE can result in quicker and more complete recovery of the RV which may lead to faster normalization of clinical parameters and functional status compared to anticoagulation alone. Purpose STORM-PE is the first RCT comparing MT using computer assisted vacuum thrombectomy (CAVT) with anticoagulation (AC) to AC alone for the treatment of acute intermediate-high risk PE. Materials and Methods STORM-PE is an international RCT where adult patients aged ≥18 years were randomized 1:1 to treatment with either CAVT with AC or AC alone. Acute (symptoms ≤14 days) intermediate-high risk PE was confirmed by right-to-left ventricular (RV/LV) ratio ≥1.0 on CTPA and elevated cardiac biomarkers. The primary endpoint analysis tested for superiority of CAVT with respect to the change in RV/LV ratio at 48 hours per a blinded core lab. Technical success was defined as the ability of the catheter to access the target thrombus. Core lab also assessed PA obstruction index (MMS and RMMS) and contrast of reflux into the IVC. Clinical parameters included vital signs and NEWS2 score (risk of clinical deterioration). Secondary endpoints included composite major adverse events (MAEs) within 7 days, assessed by an independent clinical events committee, and functional assessments. Results Among 100 patients across 22 sites, the baseline characteristics were comparable between the CAVT (N=47) and AC arm (N=53). At 48 hours, the reduction in RV/LV ratio was greater in CAVT than AC (0.52±0.37 vs 0.24±0.40, respectively; difference, 0.27 95% CI, 0.12, 0.43; p0.001). The percent of patients that returned to normal at 48 hours (RV/LV ratio ≤1.0) was 2.9 times higher in the CAVT than AC arm (CAVT vs AC, 39.1% vs 13.5%, p=0.005). Vital signs, PA obstruction and reflux into IVC at 48 hours all showed greater improvement in the CAVT arm. MAE rates at 7 days were similar (CAVT vs AC, 4.3% n=2 vs 7.5% n=4). Functional endpoint data from additional follow-up visits will be available at the time of the meeting. Conclusion STORM-PE is the first RCT to compare MT with AC vs AC alone. The CAVT arm had superior reduction in RV/LV ratio and a comparable safety profile to the AC arm. Treatment using CAVT with AC also resulted in early physiological recovery and greater reduction in PA obstruction compared with AC alone. These findings reinforce the role of MT as an effective treatment strategy. Functional data to better understand the impact on PE beyond the acute phase will be available at the time of the meeting.