Medical Device Daily

Abiomed (Danvers, Massachusetts) reported that the first patient was enrolled in its MINI-AMI prospective, randomized, controlled multi-center study.

The med-tech firm said that the patient was enrolled at the Texas Heart Institute at St. Luke's Episcopal Hospital (Houston) and implanted by Guilherme Silva, MD.

“This is a feasibility study which will assess the role of 24-hours of direct unloading of the left ventricle with Impella 2.5 support and whether it can reduce infarct size in patients with ST-elevation myocardial infarction (STEMI) without cardiogenic shock,“ Aimee Maillett corporate communications manager for Abiomed told Medical Device Daily via e-mail.

Patients will be randomized to PCI+Impella vs. PCI-only arms. The study will assess the infarct size using a magnetic resonance imaging (MRI) technique.

“The study will enroll a total of 60 acute myocardial infarction (AMI) patients requiring primary PCI, including 10 roll-in patients at a maximum of five institutions,“ Maillett said. “The primary endpoint of the study will be a cardiac MRI-assessed ratio of the final infarct area to the total area of myocardium that was at risk.“

The company said that the study will give it a first look at the potential benefit of Impella in this large patient population, which is currently untreated by any type of direct ventricular support.

“This study is not powered to show a statistical difference in the primary endpoint, the results will provide guidance towards future larger investigations, which means we could potentially expand the exploration to a larger patient population to determine if direct unloading could treat this patient population,“ she said.

STEMI patient population, which represents 330,000 patients a year, according to the American College of Cardiology (ACC; Washington) and American Heart Association (AHA; Dallas) 2009 Guidelines for STEMI and percutaneous coronary intervention (PCI). Although this study is not powered to show a statistical difference in the primary endpoint, the results will provide guidance towards future larger investigations.

The company said that also relative to this stable STEMI patient population, results were recently released from the Counterpulsation to Reduce Infarct Size Pre-PCI Acute Myocardial Infarction (CRISP AMI) trial. The CRISP AMI trial determined that routine intra-aortic balloon pump (IABP) placement prior to reperfusion in patients with STEMI without cardiogenic shock, did not reduce myocardial infarct size. A total of 337 patients were randomized at 30 sites, with one group receiving IABP+PCI and the other group receiving PCI treatment alone. The median infarct size was 37.5% in patients treated with PCI-only and trended larger in the IABP+PCI arm with 42.1% infarct size (P=0.06).

Although the recently published CRISP AMI results did not show an infarct size reduction or clinical benefit of IABP and further discourages its routine use in this category of patients, the study itself has provided insight on the extent of the infarct size in stable STEMI patients and measuring outcomes of AMI beyond the survival benefit.

“The large infarcts observed in the CRISP AMI trial overall emphasize a significant clinical need for patients who are treated within recommended door-to-balloon times and still sustain significant myocardial damage. It is a great example of the need for an effective myocardial salvage strategy which can be provided through direct ventricular unloading by a device such as Impella,“ said Jeff Moses, MD, Columbia University Medical Center/New York-Presbyterian Hospital and co-principal investigator of the MINI-AMI study.

The CRISP-AMI trial results were published online by the Journal of the American Medical Association.

The MINI-AMI trial differs from the PROTECT II evaluation of the device, a study which was ended when the company said that it appears as if physician behavior was substantially different in each subgroup of the study, likely in part due to perceived superiority of support offered by the Impella device.

The company cited over-anxious physicians as the reason why it pulled out of the study.

“This study examines a completely different patient population than PROTECT II, which studied patients in the prophylactic setting,“ Maillett said.

The Impella device received 510(k) clearance from the FDA in June 2008 for partial circulatory support for periods up to six hours.

It was initially developed in Aachen, Germany, by Impella CardioSystems (Aachen Germany). Abiomed acquired Impella CardioSystems in the Spring of 2005 for $1.8 million in cash (MDD, April 28, 2005).

Now approved in more than 40 countries, including in Europe under the CE mark, Impella 2.5 has been used to treat more than 1,700 patients worldwide and has been the subject of more than 50 peer-reviewed publications.

Omar Ford, 404-262-5546;