Bioengineered stent comes up short in STEMI patients, more data needed

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ORLANDO, Fla.—The Genous stent's novel coating is designed to reduce both restenosis and stent thrombosis. In a small trial, however, it demonstrated increased rates of both, when compared with a third-generation bare-metal stent, according to research presented during the i2 Summit at the American College of Cardiology (ACC) 58th annual scientific sessions.

"The results have to be interpreted cautiously because this is a small, single-center study," said lead investigator Pavel Cervinka, MD, 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."

In the Randomized Comparison of Genous Stent Versus Chromium-Cobalt Stent for Treatment of ST-Elevation Myocardial Infarction (GENIUS-STEMI) trial, researchers studied 100 consecutive STEMI patients. They randomized equal numbers of patients to the Genous stent (OrbusNeich) and a cobalt-chromium bare-metal stent (BMS).

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 (DES), Cervinka said. The endothelial progenitor cells (EPCs) attached to the stent are naturally elevated in response to arterial injury and have the capacity to differentiate into mature endothelial cells. The hypothesis is that the EPC coating will accelerate the healing process, protect against stent thrombosis and minimize restenosis. Previous data from non-randomized studies and clinical registries have been promising, Cervinka said.

Researchers followed-up patients with angiography and intravascular ultrasound (IVUS). Both groups received dual-antiplatelet therapy for 30 days.

Cervinka and colleagues found that at 30 days, the combined rate of major adverse cardiac events (MACE)--defined as MI, cardiovascular death and target lesion revascularization (TLR)-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 BMS (24 vs. 10 percent), mainly due to higher TLR, which was statistically higher in the Genous arm (14 vs. 4 percent).

IVUS showed larger amounts of tissue overgrowth inside the Genous stent, although the difference was not statistically significant, Cervinka said. 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 BMS.

The researchers concluded that use of the Genous EPC capture stent in patients suffering from an acute MI is feasible and safe, while expressing caution over the unfavorable results compared to the BMS.

"The rate of late stent thrombosis in the Genous group is worrisome," Cervinka concluded. "Before generalizing these results, a large randomized trial is needed to finally address this issue. Until then, the EPC stents should be avoided in patients with STEMI."