Results of the FLASH registry demonstrate the “excellent safety profile” of the FlowTriever system (Inari Medical) in 800 “real-world” patients. This is according to Catalin Toma (University of Pittsburgh Medical Center, Pittsburgh, USA), who presented outcomes for the full US cohort of FLASH at the 2022 Transcatheter Cardiovascular Therapeutics meeting (TCT; 16–19 September, Boston, USA). The results were simultaneously published in EuroIntervention.
Toma reported a 1.4% major bleeding rate and 0.4% rate of other major adverse events (MAEs) in what the presenter described as the largest prospective interventional study in pulmonary embolism (PE). All-cause mortality was <1% at the 30-day visit in this “real-world” population with prevalent baseline predictors of mortality, the presenter added, noting also that haemodynamics improved on-table, acute vitals and right ventricular (RV) strain normalised, and clinical recovery continued through six months.
The presenter noted that acute all-cause mortality following PE has remained high (>10%) over two decades, adding that, following PE, the 30-day readmission rate is nearly 25%, and up to half of patients report persistent dyspnoea, exercise intolerance, and/or functional limitations at three to six months.
According to Toma, guidelines suggest considering advanced therapies, including mechanical thrombectomy, when thrombolytics fail or are contraindicated, or haemodynamic deterioration occurs. However, he said, major bleeding risks with thrombolytic-based treatment strategies remain a concern, and their use is limited by corresponding contraindications and consequent intensive care unit (ICU) monitoring.
Mechanical thrombectomy can rapidly extract thrombus and relieve RV strain without thrombolytics, the presenter informed the TCT audience, stating that “additional data on the risk-to-benefit ratio could shift the standard of care”. One example of a mechanical thrombectomy device is FlowTriever, he highlighted, noting that this system is 510(k)-cleared by the US Food and Drug Administration (FDA) and CE mark-approved for the treatment of PE.
FLASH is a prospective, multicentre, single-arm registry designed to evaluate the safety and effectiveness of the FlowTriever system for treatment of PE through six months, with the decision to intervene being at the discretion of treating physicians or local PE response team (PERT). The primary endpoint is an MAE composite endpoint of device-related mortality within 48 hours, major bleeding within 48 hours, and intraprocedural device- or procedure-related adverse events.
At TCT, Toma reported outcomes for the full US cohort. In terms of the primary outcomes, he relayed a primary MAE rate of 1.8% (14/788), which combined a 0% rate of device-related deaths (0/788), 1.4% rate of major bleeding (11/788), and 0.4% rate of intraprocedural adverse events (3/788). The presenter also communicated all-cause mortality data, noting rates of 0.3% at the 48-hour visit (2/794), 0.8% at the 30-day visit (6/734), and 5% rate at the six-month visit (28/588). Importantly, the procedure led to significant improvement in invasive haemodynamics with decreased pulmonary pressures and improved cardiac output. Finally, Toma revealed that the rate of all-cause readmissions at the 30-day visit was 6.2%, with 1.4% related to PE treatment (10/711) and 4.8% unrelated to PE treatment (34/714).
Looking ahead, Toma highlighted that “data from the ongoing PEERLESS randomised controlled trial will provide important evidence regarding the safety and effectiveness of FlowTriever mechanical thrombectomy compared with catheter-directed thrombolysis”.