Mechanical thrombectomy for PE: What's the evidence?

PEERLESS trial tests thrombectomy vs catheter-directed thrombolysis

Pulmonary embolism and its recommended therapies are stratified according to risk:

• Patients with massive pulmonary embolism (i.e., hypotension) generally receive systemic thrombolytics, because their risk of death is higher than their bleeding risks from tPA.

• Patients with mild, low-risk PEs receive anticoagulation, because thrombolytics’ bleeding risk would far outweigh any potential benefit. 

The optimal approach to management of patients with intermediate-risk pulmonary embolism remains unknown. Intermediate-risk patients are generally defined as having clinically significant PE without shock but with elevated troponin and acute right ventricular strain (i.e., systolic dysfunction) on echocardiogram or CT.

This is a highly heterogeneous group. Most will do well with anticoagulation alone, but it’s believed that more severely ill intermediate-risk patients can benefit from catheter-directed thrombolysis (CDT), widely performed at tertiary centers using the EKOS™ system or its competitors.

Mechanical thrombectomy—aspirating clot without injecting thrombolytics—has generally been considered as an experimental or salvage therapy to be considered if thrombolysis has failed.

Inari Medical has been working hard to change that. The company won FDA clearance in 2018 to market its FlowTriever™ thrombectomy device for PEs based on prospective observational data showing mechanical thrombectomy to be reasonably safe and effective at improving right ventricular function acutely after clot removal (as measured by the RV/LV ratio). 

However, any meaningful clinical benefits remained unproven.

The PEERLESS Trial

Inari sponsored and designed the PEERLESS randomized trial jointly with some of the investigators, with results published in Circulation in October 2024.