Longer-Term Outcomes Following Mechanical Thrombectomy for Intermediate- and High-Risk Pulmonary Embolism: 6-Month FLASH Registry Results

Background: Mechanical thrombectomy provides rapid hemodynamic improvements after acute pulmonary embolism (PE), but long-term benefits are uncertain. Methods: FlowTriever All-comer Registry for Patient Safety and Hemodynamics is a prospective, single-arm, multicenter registry of patients with acute PE treated with the FlowTriever System (Inari Medical). Six-month outcomes including modified Medical Research Council dyspnea scores (MMRCD), right ventricular (RV) function, 6-minute walk test distances, and PE quality-of-life scores (QoL) were assessed. Results: In total, 799 patients were enrolled and 75% completed the study with a mean follow-up of 204 ± 46 days. Demographic characteristics included 54.1% men, mean age of 61.2 years, 77.1% intermediate-high-risk PE, and 8.0% high-risk PE. All-cause mortality was 4.6% at study completion. The proportion of patients with normal echocardiographic RV function increased from 15.1% at baseline to 95.1% at 6 months (P <.0001). MMRCD score improved from 3.0 at baseline to 0.0 at 6 months (P <.0001). 6-minute walk test distances increased from 180 m at 48 hours to 398 m at 6 months (P <.001). Median PE QoL total scores were 9.38 at 30 days and 4.85 at 6 months (P <.001). Prevalence of site-reported chronic thromboembolic pulmonary hypertension was 1.0% and chronic thromboembolic disease was 1.9%. Conclusions: In this large diverse group of PE patients, 6-month all-cause mortality, chronic thromboembolic pulmonary hypertension, and chronic thromboembolic disease were low following thrombectomy with the FlowTriever system. Significant improvements in RV function, patient symptoms, exercise capacity, and QoL were observed at 6 months, suggesting that rapid extraction of thrombus may prevent long-term sequelae in patients with PE.