Background
There is growing data showing safety and effectiveness of large-bore thrombectomy for the treatment of pulmonary embolism (PE), but limited data exist on long-term outcomes. Final 6-month results are reported from the US cohort of the FLASH registry for mechanical thrombectomy in PE.
Methods
FLASH is a prospective, single-arm, multicenter registry of acute PE patients treated with the FlowTriever System (Inari Medical). Six-month clinical outcomes were assessed, including mMRC dyspnea score, right ventricular (RV) function, 6-minute walk test (6MWT) distances, and PEmb Quality of Life (QoL) scores.
Results
Of the 800 patients enrolled across 50 US sites, 54.1% were male and mean age was 61.2 years. Thrombolytic contraindications were reported in 32.1% of patients, and 77.1% were classified as intermediate-high-risk and 8.0% as high-risk. Most patients (74.8%) completed all study visits through 6-month follow-up. Previously reported acute outcomes included intraprocedural reduction in mean pulmonary artery pressure of 7.6±6.3 mmHg and a 48-hr major adverse event rate of 1.8%. All-cause mortality was 0.3% at the 48-hr visit, 0.8% at the 30-day visit, and 4.6% at study exit (median = 199 days post-treatment). Median mMRC dyspnea score improved from 3.0 at baseline to 0.0 at 6 months (
P <0.0001). The % of patients with normal RV function on echocardiography increased from 15.1% at baseline to 95.1% at 6 months (
P <0.0001), and the % of patients with RV systolic pressure ≤40mm Hg improved from 28.4% at baseline to 93.9% at 6 months. Median 6-MWT distances increased from 180 m at 48 hr to 398 m at 6 months (
P <0.0001). Median PEmb QoL Frequency of Complaints scores improved from 12.5 at 48 hr to 1.6 at 6 months (
P <0.0001). Six-month prevalence of site-reported chronic thromboembolic pulmonary hypertension was 1.0% and chronic thromboembolic disease was 1.9%.
Conclusions
Long-term mortality was low following treatment with the FlowTriever System, and significant improvements in patient symptoms, cardiac function, and quality of life were observed at 6 months. These data suggest that rapid extraction of thrombus may prevent long-term sequelae in PE patients, though comparative data relative to conservative management are needed.