Mechanical Thrombectomy for High-Risk Pulmonary Embolism: Insights From the US Cohort of the FLASH Registry

Abstract

Background: Acute mortality for high-risk, or massive, pulmonary embolism (PE) is almost 30% even when treated using advanced therapies. This analysis assessed the safety and effectiveness of mechanical thrombectomy (MT) for high-risk PE.

Methods: The prospective, multicenter FlowTriever All-comer Registry for Patient Safety and Hemodynamics (FLASH) study is designed to evaluate real-world PE patient outcomes after MT with the FlowTriever System (Inari Medical). In this study, acute outcomes through 30 days were evaluated for the subset of patients with high-risk PE as determined by the sites and following European Society of Cardiology guidelines. An independent medical monitor adjudicated adverse events (AEs), including major AEs: device-related mortality, major bleeding, or intraprocedural device-related or procedure-related AEs.

Results: Of the 799 patients in the US cohort, 63 (7.9%) were diagnosed with high-risk PE; 30 (47.6%) patients showed a systolic blood pressure <90 mm Hg, 29 (46.0%) required vasopressors, and 4 (6.3%) experienced cardiac arrest. The mean age of patients with high-risk PE was 59.4 ± 15.6 years, and 34 (54.0%) were women. At baseline, 45 (72.6%) patients were tachycardic, 18 (54.5%) showed elevated lactate levels of ≥2.5 mM, and 21 (42.9%) demonstrated depressed cardiac index of <2 L/min/m². Immediately after MT, heart rate improved to 93.5 ± 17.9 bpm. Twenty-five (42.4%) patients did not require an overnight stay in the intensive care unit, and no mortalities or major AEs occurred through 48 hours. Moreover, no mortalities occurred in 61 (96.8%) patients followed up through the 30-day visit.

Conclusions: In this cohort of 63 patients with high-risk PE, MT was safe and effective, with no acute mortalities reported. Further prospective data are needed in this population.

Keywords: aspiration thrombectomy; embolectomy; mechanical thrombectomy; percutaneous aspiration thrombectomy; pulmonary embolism.

Graphical abstract

Figure 1

Right ventricle echocardiographic assessments. (A) RV/LV ratio (mean ± SD), (B) RV systolic pressure (mean ± SD), and (C) RV function profile were evaluated from echocardiograms collected at baseline and 48-hour and 30-day follow-up visits. From available paired measurements, P values for RV/LV ratio and RV systolic pressure were calculated using Wilcoxon signed-rank tests, and P values for RV function category distributions were calculated using McNemar-Bowker tests. LV, left ventricle; RV, right ventricle; SD, standard deviation.

Figure 2

Dyspnea and quality-of-life measures. (A) Dyspnea was evaluated at baseline and 48-hour and 30-day follow-up visits using mMRC assessments in which a higher score is equivalent to more severe dyspnea. (B) Quality of life was evaluated using PEmb-QoL questionnaires collected at 48-hour and 30-day follow-ups. An outlier PEmb-QoL score at 30 days is indicated. From available paired measurements, P values for dyspnea were calculated using McNemar-Bowker tests, and the P value for quality of life was calculated using a Wilcoxon signed-rank test. mMRC, Modified Medical Research Council; PEmb-QoL, pulmonary embolism quality of life.

Central Illustration

Acute outcomes after mechanical thrombectomy for high-risk PE. (A) Diagram of a Triever catheter from the FlowTriever System crossing the right heart for thrombectomy in a pulmonary artery. (B) Thromboemboli removed from pulmonary arteries in a case example, with (C) preprocedural and (D) postprocedural pulmonary angiograms presented. PA, pulmonary artery; PE, pulmonary embolism.