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  • Mechanical Thrombectomy with FlowTriever for Pulmonary Embolism Shows Favorable Safety and Effectiveness: FLASH Registry

    Mechanical thrombectomy with the FlowTriever System has a favorable safety profile and results in improvements in hemodynamics, functional outcomes, and low 30-day mortality for intermediate- and high-risk pulmonary embolism (PE), according to data from the FLASH registry.

    Findings from the registry – which evaluated acute safety and effectiveness of mechanical thrombectomy for intermediate- and high-risk PE in a large real-world population – were reported Sunday at Transcatheter Cardiovascular Therapeutics (TCT) 2022 in Boston and published simultaneously online in EuroIntervention.

    Led by Catalin Toma, MD, from the University of Pittsburgh Medical Center Heart and Vascular Institute, the team noted that PE is a debilitating and potentially fatal disease that has seen little improvement in mortality rates in the last decade – with all-cause mortality following PE reportedly greater than 10%.

    Speaking at TCT 2022, Toma noted that the 30-day readmission rate following PE is nearly 25%, with up to half of patients reporting persistent dyspnea, exercise intolerance, and/or functional limitations at 3 to 6 months post-PE.

    He added that current European Society for Cardiology (ESC) guidelines recommend anticoagulation (AC) for intermediate-risk PE patients and systemic thrombolysis for high-risk PE patients, while also considering advanced therapies including mechanical thrombectomy when hemodynamic deterioration occurs or when thrombolytics fail or are contraindicated.

    “Mechanical thrombectomy provides the opportunity for rapid relief of right ventricular strain and symptoms following thrombus extraction. Safety and effectiveness data from large-scale clinical studies are needed, however, to determine its role in routine acute PE management,” said the authors.

    Study setup

    Toma explained that the FlowTriever System (Inari Medical, Irvine, California) is a large-bore, catheter-based mechanical thrombectomy device designed to remove thrombus from pulmonary arteries without utilizing thrombolytics – noting that the FlowTriever All-Comer Registry for Patient Safety and Hemodynamics (FLASH) was established as an all-comer, prospective, multi-center registry to evaluate the safety and effectiveness of the FlowTriever System in a real-world population of intermediate- or high-risk PE patients.

    A total of 800 patients at 50 sites in the United States were enrolled in the registry. Key exclusion criteria include patients unable to receive anticoagulation and those with a life expectancy of less than 30 days, as determined by the investigator.

    The primary endpoint was a major adverse event (MAE) composite, comprising device-related mortality or major bleeding within 48 hours of the procedure, and intraprocedural device- or procedure-related adverse events, he noted, adding that secondary safety endpoints included the individual components of the composite primary endpoint, in addition to major access site complications requiring open surgical repair, endovascular intervention, or blood transfusion and device-related serious adverse events (SAEs) as defined according to ISO 14155.

    Key findings

    Toma and colleagues reported that among 800 patients in the full U.S. cohort, 76.7% had intermediate- to high-risk PE, 7.9% had high-risk PE, and 32.1% had thrombolytic contraindications.

    Major adverse events occurred in 1.8% of patients, he reported, noting that all-cause mortality was 0.3% at 48-hour follow-up and 0.8% at 30-day follow-up, with no device-related deaths. Reported all-cause mortality at six-month follow-up was 5.0%, although follow-up is ongoing, said Toma.

    Immediate hemodynamic improvements included a 7.6 mmHg mean drop in mean pulmonary artery pressure (–23.0%, P <0.0001) and a 0.3 L/min/m2 mean increase in cardiac index (18.9%, P <0.0001) in patients with depressed baseline values.

    Most (62.6%) patients had no overnight intensive care unit stay post-procedure, he added, noting that at 48 hours, echocardiographic right ventricle/left ventricle ratio decreased from 1.23 to 0.98 (P <0.0001 for paired values) and patients with severe dyspnea decreased from 66.5% to 15.6% (P <0.0001).

    “Data from the largest prospective interventional PE study population confirms the safety of the FlowTriever mechanical thrombectomy system,” said Toma.

    “In addition, patients had rapid hemodynamic improvement with the procedure which continued through 6 months of follow-up. Ongoing randomized trials including PEERLESS will provide important insights regarding the device’s safety and effectiveness compared to other treatments.”

    The study was funded by Inari Medical, while Toma reported consulting fees/honoraria from Medtronic and Philips.


    Toma C, Jaber WA, Weinberg MD, et al. Acute Outcomes for the Full US Cohort of the FLASH Mechanical Thrombectomy Registry in Pulmonary Embolism. EuroIntervention 2022 Sep 18 (Article in press)

    Image Credit: Jason Wermers/

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