CHICAGO – An investigative heart pump for unloading the left ventricle in patients who had an ST-elevation myocardial infarction (STEMI) yielded similar safety and efficacy outcomes with a 30-minute delay in reperfusion or the standard approach of immediate reperfusion.
Courtesy Abiomed
The Impella heart pump
That’s according to results of a pilot feasibility trial presented at the American Heart Association scientific sessions.
The trial, titled the DTU (Door to Unload)–STEMI trial, evaluated the Impella CP (Abiomed) device used for unloading the left ventricle (LV). “No prohibitive safety signals that would preclude proceeding to a larger pivotal study of left ventricle unloading and delaying reperfusion for 30 minutes were identified,” said principal investigator Navin Kapur, MD, of Tufts Medical Center.
The trial evaluated 50 patients who received the Impella device in two different groups: one that underwent immediate reperfusion after LV unloading, the other that had a 30-minute delay before reperfusion. The study found no significant difference in major adverse cardiovascular or cerebral events between the two groups (there were two in the delayed group vs. none in the immediate group), and no difference in infarct size increase as a percentage of LV mass at 30 days between the groups, Dr. Kapur said.
Door-to-balloon times averaged 73 minutes in the immediate reperfusion group and 97 minutes in the delayed reperfusion group, with door-to-unload times averaging around 60 minutes in both groups. “We were able to see successful enrollment and distribution across multiple sites and multiple operators, suggesting the feasibility of this approach,” Dr. Kapur said.
He noted “one of the most important messages” of the study was that no patients in either arm required percutaneous coronary intervention. “What this suggests is that, when we look at operator behavior, operators were comfortable with initiating LV unloading and waiting 30 minutes,” Dr. Kapur said.
The primary endpoint of the trial was to determine if delayed reperfusion led to an increase in infarct size. “We did not see that,” he noted. “And among patients with an anterior ST-segment elevation sum in leads V1-V4 of more than 6 mm Hg, infarct size normalized to the area at risk was significantly lower with 30 minutes of LV unloading before reperfusion, compared to LV unloading with immediate reperfusion.”
The next step is to initiate a pivotal trial of the device, Dr. Kapur said. “The findings from the DTU-STEMI pilot trial will inform the pivotal trial based on preclinical data showing that LV unloading attenuates myocardial ischemia and also preconditions the myocardium to allow it to be more receptive to reperfusion with a reduction in reperfusion injury,” he said. The pivotal trial will have two similar arms: one using the standard of care of immediate reperfusion and the other utilizing the 30-minute delay.
In his discussion of the DTU-STEMI trial, Holger Thiele, MD, of the Leipzig (Germany) Heart Institute and the University of Leipzig, expressed concern with the lack of a standard-of-care group in the trial. “Thus, the primary efficacy endpoint on infarct size cannot be reliably compared,” he said. “Based on the small sample size, there’s no reliable information on safety.”
Dr. Kapur reported financial relationships with Abiomed, Boston Scientific, Abbott, Medtronic, and MD Start. Dr. Thiele had no financial disclosures.
SOURCE: Kapur NK et al. AHA scientific sessions, LBCT-19578