Over the past decade, catheter-based procedures such as catheter-directed thrombolysis (CDT) and large-bore mechanical thrombectomy (LBMT) have become more widely used to treat intermediate- and high-risk pulmonary embolism (PE) in order to reduce the bleeding risks associated with systemic thrombolysis. While observational studies on CDT and LBMT have both shown favorable outcomes, no prior randomized controlled trials have directly compared the two approaches. A new international randomized controlled trial has now provided evidence that LBMT is superior to CDT with respect to the hierarchically-tested aggregated outcome that includes all-cause mortality, intracranial hemorrhage, major bleeding, clinical deterioration, escalation to bailout therapy, post-procedural ICU admission, and ICU length of stay.

The PEERLESS study, conducted by researchers at Emory University Hospital (Atlanta, GA, USA), randomized 550 hemodynamically stable adults with acute PE, right ventricular dysfunction, and at least one additional clinical risk factor for adverse outcomes. All participants had no absolute contraindications to thrombolytics and were randomly assigned to either LBMT (n=274) or CDT (n=276) in a 1:1 ratio. This trial, conducted from February 2022 to February 2024, included 57 sites across the United States, Germany, and Switzerland. Participants were followed up at 24 hours, discharge (or 7 days), and at 30 days. The primary endpoint was a hierarchically tested win ratio based on five outcomes: all-cause mortality, intracranial hemorrhage, major bleeding per ISTH definition, clinical deterioration or escalation to bailout therapy, and post-procedural ICU admission and length of stay, assessed at discharge or 7 days after the procedure.

The study results, published in the journal Circulation, showed that LBMT significantly outperformed CDT in the primary endpoint, with a win ratio of 5.01 (95% CI: 3.68–6.97, p<0.001). While the rates of all-cause mortality, intracranial hemorrhage, and major bleeding were similar between the two groups, the ICU admission rate was markedly lower for LBMT patients compared to CDT patients (41.6% versus 98.6%, p<0.001). Moreover, LBMT patients had a lower incidence of clinical deterioration or escalation to bailout therapy (1.8% versus 5.4%, p=0.038). LBMT also showed better improvement in symptom scores at 24 hours, a shorter hospital stay (4.5±2.8 vs 5.3±3.9 nights; p=0.002), and fewer 30-day readmissions (3.2% versus 7.9%; p=0.03). The 30-day all-cause mortality was similar in both groups (0.4% vs 0.8%; p=0.62).

“The PEERLESS results represent the most robust evidence comparing two methods of intervention for pulmonary embolism to date,” said Wissam A. Jaber, MD, Professor of Medicine and Director of the Cardiac Cath Lab at Emory University Hospital. “LBMT was shown to be superior to CDT driven by significantly lower rates of clinical deterioration or escalation of therapy and ICU admission. LBMT was also associated with faster clinical and hemodynamic improvement at 24 hours, significantly shorter hospital stays, and fewer readmissions through 30 days.” 

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