Comparison of Ultrasound-Assisted Thrombolysis and Mechanical Thrombectomy in Patients with Intermediate-High-Risk Pulmonary Embolism

Background: Pulmonary embolism (PE) can cause right heart failure and is associated with a high mortality. Early risk stratification is critical for individualized management. In patients with intermediate-high-risk PE, guidelines recommend to consider a percutaneous catheter-directed treatment (CDT). While different techniques are available, comparisons between treatments regarding right heart function and outcome are still scarce.

Objective: To compare changes in right heart function as well as outcome in patients with intermediate-high-risk PE after catheter-directed treatment with ultrasound-assisted thrombolysis as compared to mechanical thrombectomy.

Methods: This is a retrospective, single-center study in intermediate-high-risk PE. According to the ESC guidelines, all patients had PESI class III-V, RV dysfunction and elevated cardiac troponin levels, but were hemodynamically stable. PE was confirmed by CT angiography. All patients underwent a catheter-directed treatment. One group received an ultrasound-assisted thrombolysis with the EKOS device (Boston Scientific), while the other had a mechanical thrombectomy via the FlowTriever System (Inari). Right heart function (RV-Diameter, RV-/LV-Ratio, TAPSE) assessed via transthoracic echocardiography before and after CDT as well as interventional characteristics and postinterventional hospital stay were compared.

Results: From June 2022 to April 2024, 30 patients (40% female; aged 62 ± 15 years) were diagnosed with pulmonary embolism with intermediate-high-risk and underwent a catheter-directed treatment. Most patients (90%) had bilateral pulmonary embolisms. 16 patients (53%) received an ultrasound-assisted thrombolysis with the EKOS device. 14 patients (47%) had a mechanical thrombectomy via the INARI FlowTriever System. The mean procedural time was 41 ± 19 minutes for EKOS and 106 ± 33 minutes for FlowTriever (p < 0.001). Right ventricular / left ventricular ratio reduction was -0.48 ± 0.25 in the EKOS group (p < 0.001) and -0.36 ± 0.13 in the FlowTriever group (p < 0.001) (between group difference p = 0.2). TAPSE increased by 8 mm ± 4.4 mm in the EKOS group (p < 0.001) and by 8.8mm ± 3.8 mm in the FlowTriever group (p < 0.001) (between group difference p = 0.7). The median postinterventional hospital stay was 7 days for the EKOS patients and 6 days for the FlowTriever patients (between group difference p = 0.7).

Conclusions: In patients with intermediate-high-risk PE both EKOS and FlowTriever lead to an improved right heart function with both interventions leading to a similar length of postprocedural hospital stay. Further randomized data have to discriminate differential impact of novel tools for the treatment of intermediate risk PE.