No Benefit from Microaxial Pump in Non-Shock Heart Attack

Impella CP device did not reduce heart damage in severe heart attack patients without cardiogenic shock

Mar. 29, 2026 at 2:14am

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Using a microaxial flow pump prior to and during cardiac stenting procedures for patients with severe heart attacks who don't have cardiogenic shock does not significantly reduce heart damage, according to a new clinical trial. The STEMI-Door to Unload (DTU) trial found that while the Impella CP device did not increase infarct size despite a delay in treatment, it also did not reduce heart damage compared to immediate PCI alone.

Why it matters

Many strategies have been developed to try to reduce muscle damage during cardiac stenting procedures, but almost all have failed. This is the first pivotal trial in 30 years to test the hypothesis that using a flow pump to rest the heart can reduce infarct size in high-risk heart attack patients. The findings suggest this approach may not be effective on its own, but could potentially be combined with other therapies to improve outcomes.

The details

The DTU trial focused on the Impella CP device, a FDA-approved microaxial heart pump. Researchers analyzed 527 patients with confirmed anterior STEMI who arrived within 5 hours of heart attack onset. Patients were randomized to receive the Impella CP and delayed PCI or immediate PCI without the device. The primary endpoint was a reduction in infarct size on cardiac MRI. While infarct size was slightly lower in the Impella group, the difference was not statistically significant. However, the Impella group did have higher rates of major bleeding and vascular complications.

  • The trial was conducted between December 2019 and September 2024.
  • Patients were enrolled from 55 emergency rooms across 5 countries.

The players

Gregg W. Stone

Professor of Medicine (Cardiology) at the Icahn School of Medicine at Mount Sinai and the study's co-Principal Investigator.

Impella CP

A Food and Drug Administration (FDA)-approved catheter-based percutaneous microaxial heart pump manufactured by Abiomed.

Mount Sinai Health System

New York City's largest academic medical system, which includes The Mount Sinai Hospital ranked among the best for cardiology and heart surgery.

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What they’re saying

“In medical school we learned that 'time is muscle'—and during a heart attack, every minute that the artery is not open matters.”

— Gregg W. Stone, Professor of Medicine (Cardiology) at the Icahn School of Medicine at Mount Sinai

“While infarct size with the Impella was not significantly decreased, it is important to note that neither was it increased, despite an increase in total ischemic time of approximately 47 minutes. This suggests that the device did have beneficial effects on myocardial recovery.”

— Gregg W. Stone, Professor of Medicine (Cardiology) at the Icahn School of Medicine at Mount Sinai

What’s next

These insights will lead to modifications for future studies in high-risk heart attack patients that could pave the way for improved outcomes.

The takeaway

While the microaxial flow pump is life-saving in patients with cardiogenic shock, at the present time it does not appear to reduce heart damage when used in STEMI patients without shock. However, this approach coupled with other therapies may be more effective in improving outcomes for high-risk non-shock heart attack patients.