Safety and Efficacy of Acute Pulmonary Embolism Treated Using the Inari FlowTriever: An Update

Purpose: Evaluate initial outcomes of patients with acute central pulmonary embolism (PE) treated endovascularly with mechanical thrombectomy using the FlowTriever (FT; Inari Medical, Irvine, CA) compared with those originally reported at 12 months.

Materials and Methods: This is an institutional review board–approved retrospective analysis of mechanical thrombectomy cases performed with the FT at a single institution from March 2018 to June 2019. Of the 62 patients studied, 52% were male with mean age of 61.5 years ± 16.1. Central PE (defined as clot in the pulmonary trunk, left or right main pulmonary artery, truncus anterior, or interlobar pulmonary artery) was present in 100%. Based on European Society of Cardiology guidelines, 15% (n = 9) were classified as high-risk, 61% (n =  38) intermediate-high risk, and 24% (n = 15) as intermediate-low risk. The right ventricular–to–left ventricular ratio was elevated in all patients (average, 1.7 ± 0.5). Contraindications to thrombolytics were present in 23% (14 of 62 patients). Mechanical thrombectomy was performed using the FT aspiration device with concomitant intravenous heparin. Pharmacothrombolytic agents were not used. Technical success and major adverse events were analyzed as defined by the Society of Interventional Radiology reporting standards. Aggregate outcomes were also compared with the cohort of 42 patients whose outcomes were initially reported in the Journal of Interventional Radiology after 12 months of device use.

Results: Technical success was achieved in 100%. Average mean pulmonary artery pressure improved significantly pre- to postprocedure (33.7 ± 8.7 mm Hg pre, 26.7 ± 9.0 mm Hg post; P <0.001), consistent with the original cohort. Intraprocedure reduction of mean pulmonary artery pressure was achieved in 91.4%, also unchanged from the prior cohort (88%). Complication rate (4.8%) was also similar to the prior cohort (4.6%) with 3 major adverse events: hemoptysis requiring intubation (1) and blood loss requiring transfusion (2). Again, there were no delayed procedure-related complications or deaths within 30 days of discharge. Although 100% of patients survived to discharge in the initial cohort, a single patient died in hospital in the second group from heart failure in the setting of 3-day delayed diagnosis of massive PE.

Conclusions: Initial clinical experience using the FT to perform mechanical thrombectomy shows encouraging trends with respect to safety and efficacy for the treatment of acute central, massive and submassive, PEs that are consistent at both 12 and 18 months.