WASHINGTON–New research from the FLASH registry (ClinicalTrials.gov identifier: NCT03761173) shines a light on the effectiveness of large-bore mechanical thrombectomy in managing high-risk pulmonary embolism. The study, titled "Mechanical Thrombectomy for High-risk Pulmonary Embolism: Insights from the US Cohort of the FLASH Registry," provides valuable insights into this life-saving procedure. The findings were released today in the Journal of the Society for Cardiovascular Angiography & Interventions (JSCAI). 

Pulmonary embolism (PE) is a potentially life-threatening condition caused by the blockage of blood vessels in the lungs. High-risk PE, in particular, requires immediate medical intervention. The study shows that mechanical thrombectomy can significantly improve outcomes for patients with high-risk PE. 

Mechanical thrombectomy is a minimally invasive procedure that uses specialized instruments to remove blood clots in the pulmonary arteries. Unlike traditional anticoagulant therapy alone, mechanical thrombectomy directly addresses the source of the blockage, improving outcomes for patients with PE. 

The research analyzed data from the prospective, multicenter FLASH registry, a comprehensive database that tracks the outcomes of real-world patients with PE undergoing mechanical thrombectomy using the FlowTriever System (Inari Medical). Here, acute outcomes through 30 days were evaluated for the subset of patients with high-risk PE as determined by the investigational sites. An independent medical monitor adjudicated adverse events (AEs), including major AEs (MAEs): device-related mortality, major bleeding, or intraprocedural device- or procedure-related AEs. 

Of 799 patients in the U.S. cohort, 63 (7.9%) were diagnosed with high-risk PE. Among these 63 high-risk patients, 30 (47.6%) had systolic blood pressure <90 mmHg, 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%) had elevated lactate ≥2.5 mM, and 21 (42.9%) patients had depressed cardiac index <2 L/min/m2. Immediately following mechanical thrombectomy, heart rate improved to 93.5±17.9 bpm , and mean pulmonary artery pressure improved to 24.3±9.6 mmHg. Twenty-five (42.4%) patients did not require an overnight stay in the intensive care unit, and no mortalities or MAEs occurred through 48 hours. Moreover, no mortalities occurred in 61 (96.8%) patients followed through the 30-day visit. 

The results demonstrate that the procedure is not only safe but also associated with a significant reduction in acute mortality among patients with high-risk PE, when viewed in context with the historically high mortality rates for this patient population. 

James M. Horowitz, MD, FSCAI, lead author of the study, stated, "Our findings highlight the effectiveness of mechanical thrombectomy as a first-line treatment for high-risk pulmonary embolism. By removing blood clots from the lungs, this procedure can rapidly restore blood flow and prevent fatal complications." 

Researchers state that the study further contributes to the growing body of evidence supporting the use of mechanical thrombectomy in managing high-risk PE. The insights gained from the FLASH registry pave the way for further advancements in the field of interventional cardiology and treating patients who can be stabilized for catheterization.