Prospective Multicenter IDE Study of the Next-Generation Precision Aspiration Thrombectomy System for Intermediate-Risk Pulmonary Embolism: The SYMPHONY-PE Trial

Abstract

Background: Mechanical thrombectomy offers a promising alternative to thrombolytic-based approaches for reducing thrombus burden and right heart strain in acute pulmonary embolism. This pivotal Food and Drug Administration-approval trial evaluated the safety and efficacy of the Symphony Thrombectomy System (Imperative Care, Inc, Campbell, CA) in acute intermediate-risk pulmonary embolism. Methods: Patients with intermediate-risk pulmonary embolism (systolic blood pressure ≥90 mm Hg; right ventricle-to-left ventricle ratio >0.9) were enrolled without roll-ins. The primary safety end point was the rate of major adverse events within 48 hours, defined as a composite of all-cause major bleeding, device-related mortality, and serious device-related events, adjudicated by an academic independent safety board. The primary efficacy end point was the core laboratory-assessed mean change in right ventricle-to-left ventricle ratio from baseline to 48 hours. Prespecified performance goals were set for both. Exploratory end points included immediate postprocedure change in mean pulmonary artery pressure and change in modified Miller index at 48 hours. Safety was assessed in the intention-to-treat cohort and efficacy in the modified intention-to-treat cohort, excluding patients receiving nonstudy device treatments. Results: Between December 2023 and May 2025, 109 patients were treated at 17 US centers (intention-to-treat), with 106 in the modified intention-to-treat cohort. The major adverse events rate was 0.9% (1/109), with an upper 97.5% CI of 5.7%, meeting the <15% safety goal (P<0.001). No device-related clinical deterioration, pulmonary vascular injury, or cardiac injury occurred at 48 hours; no mortality occurred through 30 days. The mean right ventricle-to-left ventricle ratio decrease was 0.44, with a lower 97.5% CI of 0.36, exceeding the >0.20 performance goal (P<0.001). Mean pulmonary artery pressure decreased from 29.1±7.2 to 22.2±6.6 mm Hg (24%) and the modified Miller index from 24.2±4.1 to 14.9±5.4 (38%), both P<0.001. Conclusions: These data support the safety and effectiveness of the Symphony Thrombectomy System in patients with acute intermediate-risk pulmonary embolism.