ENGULF Analysis Shows Reduced Blood Loss With E2’s Hēlo System in PE Procedures

May 4, 2026—A comparative analysis from the ENGULF trial demonstrated that using blood return during continuous aspiration thrombectomy dramatically reduced blood loss by 97%, while maintaining hemodynamic efficacy and improving procedural efficiency.

The analysis findings were presented as late-breaking clinical science at SCAI 2026, the Society for Cardiovascular Angiography & Interventions scientific sessions.

According to SCAI, ENGULF is a single-arm safety and feasibility study of the Hēlo catheter thrombectomy system (Endovascular Engineering, Inc. [E2]) for the treatment of pulmonary embolism. The prospective trial is conducted under an investigational device exemption.

Hēlo is designed as a blood return system (BRS) intended to allow a patient to receive their own blood after it is filtered and returned, while removing the clot by simultaneously combining the aspiration with mechanical clot disruption, noted SCAI.

The comparative analysis of 130 patients evaluated outcomes in patients treated with the Hēlo BRS (n = 40) versus those treated with standard continuous aspiration without blood return (n = 90).

As summarized in the SCAI press release, the analysis showed the following:

• The BRS reduced median blood loss by 97% compared to non-BRS treatment (10 mL vs 340 mL; P < .001).
• All BRS procedures were completed without adjunctive therapy to manage blood loss, compared with five interventions in the non-BRS group.
• The BRS group experienced no major adverse events.
• 88% of BRS procedures were completed with a single pass through the heart.

Additionally, the primary endpoint of effective blood flow was higher in the BRS group, with a hemodynamic efficacy (right ventricular–to–left ventricular reduction) of 28% compared to 25% in the non-BRS group (P = .05).

Andrew Klein, MD, an interventional cardiologist at Piedmont Heart Institute in Atlanta, Georgia, serves as National Coprincipal Investigator of ENGULF.

“This first-of-its-kind BRS permits operators to remove more thrombus without having to be concerned about blood loss,” commented Dr. Klein in the SCAI press release. “The BRS system provides confidence to operators in knowing they are returning high-quality blood back to the patient in a safer, more timely, and effective manner. This, in turn, allows operators to be more aggressive about clot removal, which should make patients feel better faster.”