The use of a microaxial flow pump before and during cardiac stenting procedures for patients with severe heart attacks who do not have cardiogenic shock does not significantly reduce heart damage, according to results presented on March 28 by Gregg W. Stone, Professor of Medicine (Cardiology) at the Icahn School of Medicine at Mount Sinai. The findings come from the "STEMI-Door to Unload (DTU)" trial, which were also published in the Journal of the American College of Cardiology.
This study is important because it addresses whether resting the heart with a device before stenting can limit damage during a major type of heart attack known as ST-segment elevation myocardial infarction (STEMI). Quick intervention is crucial for these patients, as delays or ineffective treatments can lead to greater loss of heart muscle and worse outcomes.
Stone said that many strategies have been tried over time to protect the heart during such procedures but almost all have failed. He explained that only one therapy—supersaturated oxygen—has previously shown benefit in reducing infarct size. The DTU trial focused on using an FDA-approved Impella CP microaxial flow pump made by Abiomed in patients with large anterior STEMIs who were not experiencing shock.
"The DTU trial is the first pivotal trial in 30 years that has tested this hypothesis," Stone said. "Unfortunately, infarct size, the primary endpoint of the study, was not reduced, and as expected, there were bleeding complications from the device. Thus, while the microaxial flow pump is life-saving in patients with cardiogenic shock, at the present time we do not recommend its routine use in patients with evolving heart attack without shock. However, this approach coupled with pharmacologic or other therapies may be synergistic and improve outcomes in high-risk non-shock patients with heart attacks. That is the future direction for new studies."
The randomized study included 527 patients from five countries who arrived within five hours after their symptoms began between December 2019 and September 2024. Participants either received delayed percutaneous coronary intervention (PCI) after Impella placement or immediate PCI without Impella support. Researchers found no statistically significant difference between groups regarding reduction in infarct size measured by cardiac MRI three to five days post-procedure; however, bleeding and vascular complications occurred more frequently among those treated with Impella.
"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," Stone said. "This suggests that the device did have beneficial effects on myocardial recovery... These insights will lead to modifications for future studies in high-risk heart attack patients that could pave the way for improved outcomes." Abiomed funded this research.
