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Battle of the Drug-Eluting Stents
Three rounds of sirolimus versus paclitaxel
Drug-eluting stents (DES) are superior to bare-metal stents for preventing restenosis, but few studies have compared the two DES available in the U.S.: sirolimus-eluting and paclitaxel-eluting. Three new studies have done just that.
The first was a meta-analysis of six trials in which subjects (3669 in all) were randomized to receive sirolimus- or paclitaxel-eluting stents. During clinical follow-up (range, 6–13 months), target-lesion revascularization (TLR) was required by significantly fewer sirolimus-stent recipients than paclitaxel-stent recipients (5.1% vs. 7.8%; odds ratio, 0.64). During angiographic follow-up in five trials (range, 6–8 months), restenosis rates also showed a significant advantage for sirolimus (9.3% vs. 13.1%; OR, 0.68). Stent thrombosis occurred in 1% of each group.
In one of the unpublished trials included in the meta-analysis (now published in full), researchers in Switzerland randomized, in single-blind fashion, 1012 patients to receive either sirolimus- or paclitaxel-eluting stents. The two groups had similar baseline clinical, angiographic, and procedural characteristics and the same mean number of stents per patient (1.4). Incidence of the primary composite endpoint (death from cardiac causes, MI, or TLR) at 9 months was significantly lower in the sirolimus group than in the paclitaxel group (6.2% vs. 10.8%; OR, 0.56), primarily due to fewer TLRs with sirolimus (4.8% vs. 8.3%). This finding mirrored angiographic results at 8 months, obtained in 53% of patients: The sirolimus group showed significant advantages in mean late luminal loss (0.19 mm vs. 0.32 mm with paclitaxel) and in the binary restenosis rate (6.6% vs. 11.7%). Sirolimus’ advantage over paclitaxel was greater among diabetic patients (20% of subjects) than among nondiabetics, but not significantly so.
In another randomized trial, researchers in Germany compared the two types of stents specifically in 250 diabetic patients. About half were being treated with oral hypoglycemic agents, one third with insulin, and the rest with dietary therapy alone. Follow-up angiography, obtained in 82% of subjects a mean of 196 days after stenting, showed in-segment late luminal loss (the primary endpoint) to be significantly lower with sirolimus than with paclitaxel (mean, 0.43 mm vs. 0.67 mm), yielding a significantly lower rate of in-segment restenosis (6.9% vs. 16.5%). Insulin-requiring and non–insulin-requiring patients had similar results. Rates of death and MI were similar in the sirolimus and paclitaxel groups, but the sirolimus group had a nonsignificant trend toward fewer TLRs (6.4% vs. 12.0%).
Comment: These direct comparisons of the two FDA-approved DES show a slight absolute clinical advantage for sirolimus-eluting stents, consistent with previous non–head-to-head findings that sirolimus better inhibits post-stenting neointimal hyperplasia. Editorialists note that the advantage is magnified in settings (e.g., diabetes) where neointimal hyperplasia is more marked. In all, the advantages stand despite study limitations, including incomplete angiographic follow-up, lack of long-term clinical follow-up, and insufficient power to assess important secondary endpoints such as stent thrombosis. Still, for many patients, the sirolimus stent’s clinical advantages might be outweighed by the paclitaxel stent’s greater ease of delivery and by cost differences. Also, repeat comparisons will be needed as the next generation of DES soon become available.
— Howard C. Herrmann, MD
Published in Journal Watch Cardiology September 23, 2005
Citation(s):
Kastrati A et al. Sirolimus-eluting stents vs paclitaxel-eluting stents in patients with coronary artery disease: Meta-analysis of randomized trials. JAMA 2005 Aug 17; 294:819-25.
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Windecker S et al. Sirolimus-eluting and paclitaxel-eluting stents for coronary revascularization. N Engl J Med 2005 Aug 18; 353:653-62.
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Dibra A et al. for the ISAR-DIABETES Study Investigators. Paclitaxel-eluting or sirolimus-eluting stents to prevent restenosis in diabetic patients. N Engl J Med 2005 Aug 18; 353:663-70.
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Moliterno DJ. Healing Achilles -- Sirolimus versus paclitaxel. N Engl J Med 2005 Aug 18; 353:724-7.
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