The EkoSonic Endovascular System (EKOS) demonstrates a “significant and substantial” improvement in right ventricular (RV) function in massive or submassive pulmonary embolism (PE) patients across 4 years in the retrospective EKOS PE study. The system was also associated with low rates of mortality and serious complications in the 139-patient analysis, as well as favorable quality of life (QoL) outcomes. Reporting the results on Tuesday during a Late-Breaking Clinical Trial session at Cardiovascular Research Technologies (CRT) 2025, Sameh Sayfo, MD, MBA — from Baylor Scott & White Heart Hospital, Texas — said they should prompt large-scale prospective multi-center trials. PE is a major cause of morbidity and mortality, while massive and submassive PE cases are particularly high risk. Historically, submassive PE carries a 5% to 25% mortality risk, while massive PE carries an 18% to 65% risk, said Dr. Sayfo. Massive and submassive patients often develop RV strain and potentially chronic complications, such as recurrent venous thromboembolism (25% to 33% and post-thrombotic syndrome (50%). Treatment options continue to evolve, Dr. Sayfo pointed out, including surgical thrombectomy, anticoagulation, systemic thrombolysis and large-bore aspiration devices. Boston Scientific’s EKOS was designed as a catheter-directed thrombolytic treatment option for those patients with contraindications to systemic thrombolysis, with short-term effectiveness evaluated in prior studies. However, long-term outcomes for the system had been limited, sparking the current retrospective cohort in 139 massive or submassive PE patients who underwent EKOS therapy within a single healthcare system from 2020 to 2024. All patients in the study received EKOS therapy following OPYALYSE-based dosing protocols. Massive PE was defined as having syncope, sustained systemic hypotension (systolic blood pressure < 90 mm Hg), cardiogenic shock, or resuscitated cardiac arrest, while submassive was defined as RV dysfunction (RV/LV ratio ≥ 1.0 on echocardiography, or troponin I >0.4 ng/mL) without hemodynamic shock. At baseline, the patients’ mean age was 60.8 years and the majority (55.5%) were female. PE severity was massive for 24.8% and submassive in 75.2%, with a median Pulmonary Embolism Severity Index (PESI) score of 79.0 [IQR 65.0-98.5]. During the index hospitalization, one retroperitoneal bleed (0.7%) and one stroke (0.7%) were observed. The primary outcome measure, all-cause mortality, occurred in 7.2% of patients at a mean follow-up of 26.5 ± 17.2 months. There was a 0.7% adverse events rate, caused by incidence of major bleeding and ischemic stroke, and a 5.1% readmission rate overall. Secondary endpoints included reduction in the RV to left ventricular (RV/LV) ratio, which dropped from 1.13 ± 0.24 to 0.83 ± 0.19 (p<0.01), and residual RV dysfunction, which was evident in 16 (11.5%) patients. Those patients exhibited moderate to severe residual dysfunction. Overall, RV dysfunction went from 80.3% pre-EKOS, which was classed as severe in 37.2%, to 20.8% post-EKOS, in which 4.8% were severe, said Dr. Sayfo. QoL as assessed using the PEmb-QoL questionnaire was another secondary outcome measure. Of the 52 patients who completed the QoL survey at a mean follow-up of 37.2 ± 12.1 months, minimal residual symptoms, limited functional interference and improved lung health were reported, the study’s researchers noted. “EKOS is a viable long-term strategy for high-risk PE, especially with contraindications to systemic thrombolysis,” Dr. Sayfo — who reported financial and advisory board ties with the device’s manufacturer — concluded. Image Credit: Bailey G. Salimes Image Caption: Sameh Sayfo, MD, MBA, presents during a Late-Breaking Clinical Trial session at Cardiovascular Research Technologies (CRT) 2025 on Tuesday.