The main limitation of coronary revascularization is the need for repeated treatment because of restenosis of the vessel. One potential approach to avoiding retreatment is to use a stents that elute sirolimus, which inhibits lymphocyte and smooth muscle cell proliferation.

Recent trial results show that the sirolimus-eluting stent is promising for preventing neointimal events and avoiding major cardiac events. Investigators reported results of the Sirolimus-Eluting Stent (SIRIUS) trial in September 2002. The randomized study included 1,058 patients who received either a sirolimus-eluting stent (Cypher) or a bare metal stent (Bx Velocity). At 8 months, angiographic follow-up revealed a 3.2% rate of in-stent restenosis, a 91% reduction versus the control arm. In-lesion restenosis was 8.9%, or 75% lower than in the control arm. Event-free survival at 9 months was 92.7%, versus 80.7% for the bare metal stent group (p<0.001).

The Canadian Multi-Center, Randomized, Double-Blind Study of the Sirolimus-Eluting Stent (C-SIRIUS) included 100 patients with long stenoses in small vessels. Each patient had a single de novo coronary lesion between 15 and 32 mm in length. The vessel diameter was between 2.5 and 3.0 mm. All patients had angina or documented silent ischemia.

Investigators randomized these 100 patients to receive either the sirolimus-eluting stent or an uncoated Bx Velocity stent. All patients received clopidogrel daily for 2 months. Angiographic follow-up was at 8 months and clinical follow-up at 9 months. The primary endpoint was in-lesion minimal lumen diameter at 8 months.

Baseline demographics were comparable between the two groups. Approximately 69% were men and the mean age was about 60 years. Slightly fewer patients in the control group received multiple stents (34% versus 46%) but the difference was not statistically significant.

Dr. Schampaert reported that at 8 months, the sirolimus stent treatment resulted in a 40% increase in minimal lumen diameter. This result was statistically significant. In addition, there was a statistically significant reduction in late loss, and not a single case of restenosis in the sirolimus stent group.

In-lesion angiographic results showed a similar trend. This area includes the stent plus a region 5 mm proximal and distal to the stents. There was a 35% increase in minimal lumen diameter, 87% late loss reduction and 95% restenosis reduction. That single case of restenosis in the sirolimus-eluting stent group occurred at the proximal edge of the lesion. It occurred even though there was a significant reduction in late loss for that segment.

There were few major adverse cardiac events in either group. Investigators reported these events occurred in 2 patients (4%) in the sirolimus-eluting stent group and 9 patients (18%) in the control group (p=0.05). There were no deaths or Q-wave myocardial infarctions in either group.

Survival free of a clinically driven target vessel revascularization was 96% in the sirolumis-eluting stent group, versus 82% in the bare metal stent group. This represented an absolute risk reduction of 14% (p=0.027).

The small sample size of 100 patients limits this study. However, Dr. Schampaert said the sirolimus-eluting stent does appear to prevent in-stent restenosis in this very high risk group. These results now extend the positive benefits that occurred in earlier trials to this patient population.

The sponsor of the C-SIRIUS study was Cordis, Johnson & Johnson Company, Canada.