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Sirolimus-eluting stents safe, effective in very long-term follow-up, new findings demonstrate

Thursday, December 18 2008 | Comments

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What's This? Among patients with in-stent restenosis (ISR), implantation of sirolimus-eluting stents appears to remain safe and effective at very long-term clinical follow-up, according to findings from the RIBS-II study.

To assess the long-term safety and efficacy of sirolimus-eluting stents in patients with ISR, researchers evaluated clinical outcomes in the RIBS-II trial after >1 year of follow-up, a prespecified secondary endpoint of the original study. During the RIBS-II trial, 150 patients with ischemia secondary to bare-metal ISR were randomized to receive a sirolimus-eluting stent (n=76) or to undergo balloon angioplasty (n=74). After intervention, patients received aspirin indefinitely and clopidogrel 75 mg/day for >=9 months.

At 1 year, the rate of event-free survival was higher in the sirolimus-eluting stent group than in the balloon angioplasty group (88% vs 69%; P<.005), with events defined as death, myocardial infarction (MI), or target vessel revascularization (TVR).

Clinical follow-up lasted >1 year in 146 patients (97.3%) and >3 years in 145 patients (96.7%). The early benefit achieved with sirolimus-eluting stents was maintained during long-term follow-up, the authors noted.

At long-term follow-up, the event-free survival rate was 76% in the sirolimus-eluting stent group compared with 65% in the balloon angioplasty group (P=.019). The hazard ratio (HR) for any major event with balloon angioplasty (vs sirolimus-eluting stents) was 1.92 (95% CI, 1.03-3.59). This increased risk was largely the result of a higher requirement for TVR (HR, 2.35; 95% CI, 1.17-4.70). In multivariate analysis, having received a sirolimus-eluting stent was an independent predictor of event-free survival.

Late events were rare and occurred at similar rates in the 2 groups, the investigators explained. After the first year, 3 patients died (1 from the sirolimus-eluting stent group and 2 from the balloon angioplasty group), 5 had an MI (4 from the sirolimus-eluting stent group and 1 from the balloon angioplasty group), and 7 required TVR (4 from the sirolimus-eluting stent group and 3 from the balloon angioplasty group).

Throughout follow-up, there were 2 cases of definitive stent thrombosis, 2 cases of probable stent thrombosis, and 1 case of possible stent thrombosis in the sirolimus-eluting stent group compared with 1 case, 0 cases, and 3 cases, respectively, in the balloon angioplasty group. However, the authors acknowledged, 2 of the 4 cases of stent thrombosis in the balloon angioplasty group (1 definitive and 1 possible case) occurred only after sirolimus-eluting stent implantation was required for recurrent ISR at the target lesion. If these 2 cases were attributed to stent implantation rather than balloon angioplasty, a trend favoring balloon angioplasty was observed.

Although the investigators acknowledged certain limitations to their study, including a relatively small sample size, they concluded, "The very long-term clinical follow-up of this randomized clinical trial demonstrates that in patients with ISR, the use of sirolimus-eluting stents is safe and highly effective, providing long-term clinical results superior to balloon angioplasty." (Alfonso F, et al. J Am Coll Cardiol 2008;52:1621-1627.)

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