Drug-Eluting Stent Selection
Abstract & Commentary
By Michael H. Crawford, MD, Professor of Medicine, and Chief of Clinical Cardiology, at the University of California, San Francisco. Dr. Crawford is on the speaker's bureau for Pfizer.
Source: Kastrati A, et al. Predictive Factors of Restenosis After Coronary Implantation of Sirolimus- or Paclitaxel-Eluting Stents. Circulation. 2006;113:2293-2300.
Although drug-eluting stents (DES) have markedly reduced in-stent restenosis, it is not zero and it has not been uniform across different patient populations. Thus, Kastrati and colleagues from Munich, Germany, analyzed clinical and angiographic patient characteristics that may predict in-stent restenosis in DES. The 1845 patients with 2093 lesions had successful elective, non-left, main-stent placement for de novo lesions in native vessels. Early on, sirolimus-eluting stents were available, but when paclitaxel stents eventually became available, the patients were randomized between the 2 stents. Adjuvant therapy included 600 mg of clopidogrel at least 2 hours before the procedure and 500 mg of intravenous aspirin. Afterward, aspirin 100 mg twice a day indefinitely and clopidogrel 75 mg once a day for at least 6 months were given. The primary end points were target lesion revascularization (TLR) and angiographic restenosis (≥ 50% stenosis in-segment). Likely factors that may predict the primary end points were tested by multivariate analysis.
Results: Overall, 1030 patients received sirolimus stents and 815 received paclitaxel stents in 1151 and 942 lesions, respectfully. Early (< 30 days) stent thrombosis was < 1% in both groups. Protocol driven coronary angiography was accomplished in 1495 patients (81%) at an average of 193 days post procedure. The patients who underwent follow-up angiography were younger and more frequently men. Angiographic restenosis was found in 13% of the patients. Total occlusion was observed in 1.2% of the sirolimus stents and 2.4% of the paclitaxel stents (P = .05). TLR was done in 9% of the patients. Vessel size, final diameter stenosis, and type of stent were the strongest predictors of restenosis. The odds ratio for restenosis with a sirolimus stent was 0.60 (95%; CI, 0 .44 to 0.81) and TLR was 0.67 (0.49-0.91), as compared to paclitaxel stents. Further analysis showed that stent type was only important for vessel sizes < 2.6 mm, where TLR was twice as common with paclitaxel stents (15% vs 8%). Kastrati and colleagues concluded that vessel size and DES type are predictive of in-stent restenosis and TLR, with DES type being most important in smaller vessels.
Commentary
Technical developments with DES have reached the point where there are very few technical differences between sirolimus and paclitaxel stents. Kastrati et al asked the question whether there were clinical reasons to pick one over the other. Prior to this study there were a few reasons to choose one stent over the other. Sirolimus stents require a minimum of 3 months of intense antiplatelet therapy, whereas, paclitaxel stents require 6 months. Thus, if surgery were needed soon and platelet therapy needed to be withheld, using a sirolimus stent made sense. Also, if the patient already has one brand of DES implanted and is doing well, it makes sense to use the same brand again. Finally, some data suggest that when treating in-stent re-stenosis with another stent, sirolimus stents provide better results. This study suggests that small coronary vessel size may be another reason to select sirolimus stents. Interestingly, there were no other clinical, vessel, or lesion characteristics that were important in stent selection.
There were limitations to this study. It is impossible to blind the operators to the type of stent being implanted, so some procedural bias could be operant. Only one type each of sirolimus and paclitaxel stents were tested, but these are the most commonly used. Clopidogrel load was given > 2 hours before the procedure, and 600 mg was used. Also, 500 mg of aspirin was given intravenously. This is not the US practice, and could have influenced the results. Also, almost one in 5 patients had no angiographic follow-up, and the early part of the study was not randomized. However, until more data are available, vessel size can be added to the considerations for DES type selection.
Although drug-eluting stents (DES) have markedly reduced in-stent restenosis, it is not zero and it has not been uniform across different patient populations.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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