Percutaneous Thrombectomy in Emergency Department Patients with Pulmonary Embolism: The FLARE ED Sub-study

Abstract

Background: The FlowTriever Pulmonary Embolectomy Clinical Study (FLARE) was a multicenter, single-arm trial that demonstrated effectiveness of the FlowTriever percutaneous pulmonary embolectomy system in reducing right ventricular/left ventricular (RV/LV) diameter ratio in patients with acute intermediate-risk pulmonary embolism (PE). Patients diagnosed in emergency departments (EDs) with acute PE may have a different presentation from those diagnosed in an in-hospital setting.

Objectives: The goal of this sub-study was to evaluate the safety and effectiveness of mechanical embolectomy in ED patients with acute intermediate-risk PE.

Methods: ED patients with acute PE and RV/LV ratio ≥ 0.9 enrolled in the FLARE study were core laboratory analyzed. The primary efficacy endpoint was the change in RV/LV ratio from baseline to 48 h post procedure. The change in RV/LV ratio of patients with nonelevated cardiac troponin (cTn) and zero simplified PE Severity Index (sPESI) score (normal cTn-sPESI: intermediate-low risk) was also examined. Major adverse events (MAEs) included major bleeding, device-related death or clinical deterioration, and vascular or cardiac injury.

Results: Seventy-six ED patients were included. Thirty-nine had a sPESI score of ≥ 1 and 32 had elevated cTn. The median preprocedure RV/LV ratio for all ED patients was 1.50 (0.88-2.52), with a change by -0.37 postprocedure (p < 0.001.) Three patients experienced MAEs. Seventeen patients (22.4%) presented with normal cTn-sPESI and had an RV/LV ratio reduced by 0.27 (p < 0.001) after embolectomy.

Conclusion: ED patients with intermediate-risk PE had significant improvement in their RV/LV ratio and low complication rates when treated with mechanical embolectomy, irrespective of their baseline cTn-sPESI risk score.

Keywords: FlowTriever; percutaneous mechanical thrombectomy; pulmonary embolism; right heart strain.