Percutaneous mechanical thrombectomy in a real-world pulmonary embolism population: Interim results of the FLASH registry

Abstract

Objectives: The FlowTriever All-Comer Registry for Patient Safety and Hemodynamics (FLASH) is a prospective multi-center registry evaluating the safety and effectiveness of percutaneous mechanical thrombectomy for treatment of pulmonary embolism (PE) in a real-world patient population (NCT03761173). This interim analysis reports outcomes for the first 250 patients enrolled in FLASH.

Background: High- and intermediate-risk PEs are characterized by high mortality rates, frequent readmissions, and long-term sequelae. Mechanical thrombectomy is emerging as a front-line therapy for PE that enables immediate thrombus reduction while avoiding the bleeding risks inherent with thrombolytics.

Methods: The primary endpoint is a composite of major adverse events (MAE) including device-related death, major bleeding, and intraprocedural device- or procedure-related adverse events at 48 h. Secondary endpoints include on-table changes in hemodynamics and longer-term measures including dyspnea, heart rate, and cardiac function.

Results: Patients were predominantly intermediate-risk per ESC guidelines (6.8% high-risk, 93.2% intermediate-risk). There were three MAEs (1.2%), all of which were major bleeds that resolved without sequelae, with no device-related injuries, clinical deteriorations, or deaths at 48 h. All-cause mortality was 0.4% at 30 days, with a single death that was unrelated to PE. Significant on-table improvements in hemodynamics were noted, including an average reduction in mean pulmonary artery pressure of 7.1 mmHg (22.2%, p < 0.001). Patient symptoms and cardiac function improved through follow-up.

Conclusions: These interim results provide preliminary evidence of excellent safety in a real-world PE population. Reported outcomes suggest that mechanical thrombectomy can result in immediate hemodynamic improvements, symptom reduction, and cardiac function recovery.

Keywords: hemodynamics; mechanical thrombectomy; percutaneous intervention; pulmonary embolism.

Conflict of interest statement

Catalin Toma received advisory board funds from Phillips/Volcano. Matthew C. Bunte received research support from Inari Medical. Wissam A. Jaber received small consultation fees from Inari Medical, advisory board funds from Medtronic, and proctorship fees from Abbott Vascular. Jeffrey Chambers and Herman Kado are consultants for Inari Medical. Brian Stegman is a speaker/proctor for Edwards Lifesciences, a proctor and consultant for Medtronic, and a consultant for Cardionomics. Daniel A. Leung received speaker/consultant fees from Boston Scientific. Mitchell Weinberg is a consultant for Magneto Thrombectomy Solutions, Boston Scientific, Medtronic, Terumo Microvention, and Neptune Medical. Robert E. Beasley has received consultant fees and/or grant or research support from Abbott, BSCI, Cardinal Health/Cordis, Centerline BioMedical, Cook Medical, CR BARD/Becton Dickinson, CSI, Endologix, Inari Medical, Medtronic, MicroMedical Solutions, Penumbra, Philips/Volcano/Spectranetics, Terumo/Bolton, and WL Gore. Michael A. Brown received small speakers' fees from Inari Medical.

© 2022 The Authors. Catheterization and Cardiovascular Interventions published by Wiley Periodicals LLC.

Figures

Figure 1

Representative FLASH case of a high‐risk PE patient treated with the FlowTriever System. Pre‐thrombectomy pulmonary angiograms showed filling defects in the right (A) and left (B) PAs which resolved following treatment in (C) and (D). Extracted thrombus is shown in (E). Case images provided by Dr. Hriday Shah (St. Joseph Mercy, Ann Arbor, MI). PA, pulmonary arteries; PE, pulmonary embolism [Color figure can be viewed at wileyonlinelibrary.com]

Figure 2

On‐table hemodynamic improvements. (A) Mean PA pressure, (B) total pulmonary vascular resistance, and (C) cardiac index in patients with baseline values below 2.0 l/min/m2 were all significantly improved immediately following FlowTriever thrombectomy. CI, cardiac index; FT, FlowTriever; PA, pulmonary artery; TPVR, total pulmonary vascular resistance. All p values are based on available paired assessments using Wilcoxon signed‐rank tests [Color figure can be viewed at wileyonlinelibrary.com]

Figure 3

Heart rate and dyspnea improvements through 30 days. (A) Heart rate is reported as the in‐hospital pre‐procedure average (“Pre‐FT”), the in‐hospital post‐procedure average (“Post‐FT”), and the value at the 30‐day visit (“30d”). p values are based on Wilcoxon signed‐rank tests for follow‐up values paired with Pre‐FT values. (B) Dyspnea severity is reported for patients who were dyspneic before treatment, showing dyspnea scores pre‐procedure and at 48 h and 30 days postprocedure based on the modified Medical Research Council (mMRC) dyspnea scale. BPM, beats per minute; FT, FlowTriever [Color figure can be viewed at wileyonlinelibrary.com]

Figure 4

Improved RV size and function assessed via echocardiography. (A) Mean RV/LV ratio, (B) mean RV systolic pressure, (C) RV systolic dysfunction grades, and (D) RV dilatation grades each showed significant improvement at follow‐up, which represents a composite of the latest assessment available for each subject. Median follow‐up time was 32.0–33.5 days, depending on the variable. In (A) and (B), all available preprocedure and follow‐up data are shown, though statistical comparisons are limited to patients with paired assessments (RV/LV ratio: n = 86 with mean difference of −0.36; RV systolic pressure: n = 61 with mean difference of −19.1 mmHg). p values are calculated from Wilcoxon signed‐rank tests. FT, FlowTriever; LV, left ventricle; RV, right ventricle [Color figure can be viewed at wileyonlinelibrary.com]