Novel Stent Designed to Aid Heart Attack Patients Needs Further Study
April 9, 2009 - Researchers say a larger trial is needed to effectively test a novel stent designed to speed arterial healing in heart attack patients by attracting the body’s own circulating stem cells to create a protective layer over the implanted device.
Research from the Randomized Comparison of Genous Stent Versus Chromium-Cobalt Stent for Treatment of ST-Elevation Myocardial Infarction (GENIUS-STEMI) trial was presented during the i2 Summit the ACC’s 58th annual scientific session last week in Orlando, FL.
In the trial, researchers evaluated the investigational stent’s ability to reduce both restenosis of the treated artery and blood clot formation on the stent (stent thrombosis). Instead, the study demonstrated increased rates of both, when compared to a third-generation bare-metal stent.
“The results have to be interpreted cautiously because this is a small, single-center study,” said Pavel Cervinka, M.D., Ph.D, an associate professor and head of cardiology at Masaryk Hospital and University of J.E. Purkyne, Ústí nad Labem, Czech Republic. “However, in a head-to-head comparison, the chromium-cobalt stents were doing better than the Genous stent at six month follow-up.”
For the GENIUS-STEMI study, 100 consecutive patients with ST-elevation myocardial infarction (STEMI) were studied. Equal numbers of patients were randomly assigned to undergo stenting with the Genous EPC (endothelial progenitor cells) capture stent or a chromium-cobalt stent.
The Genous stent is designed to reduce the risk of restenosis while overcoming the tendency toward late stent thrombosis that has shadowed drug-eluting stents. Coated with an antibody, the Genous stent attracts circulating EPCs. These EPCs are naturally elevated in response to arterial injury and have the capacity to differentiate into mature endothelial cells, like those lining the inner surface of arteries. It is hoped that this unique characteristic will accelerate the healing process, protect against blood clot formation, and minimize restenosis in stented arteries. Previous data from non-randomized studies and clinical registries have been promising.
During follow-up, researchers evaluated the patients clinically as well as with angiographic imaging and intravascular ultrasound. They found that at 30 days, the combined rate of major adverse cardiac events (MACE)—defined as heart attack, cardiovascular death, and repeat treatment of the target lesion—was comparable in the two groups. At six months, however, there was a significantly higher MACE rate among patients treated with the Genous stent when compared with those treated with the chromium-cobalt stent (24 percent vs.10 percent; p=0.03). Patients treated with the Genous stent also had a statistically higher rate of repeat procedures in the originally targeted lesion (14 percent vs. 4 percent; p=0.04).
Intravascular ultrasound showed larger amounts of tissue overgrowth, the most common cause of restenosis, inside the Genous stent, although the difference was not statistically significant. In addition, there were three cases of late stent thrombosis in patients treated with the Genous stent (6 percent), but none in patients treated with the chromium-cobalt stent.
The researchers concluded that use of the Genous EPC capture stent in patients suffering from an acute heart attack is feasible and safe, while expressing caution over the unfavorable results compared to the chromium-cobalt stent.
“The rate of late stent thrombosis in the Genous group is worrisome,” Dr. Cervinka said. “Before generalizing these results, a large randomized trial is needed to finally address this issue.”
For information: www.acc.org