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Outcomes in the era of bare-metal stents vs the era of drug-eluting stents.

To the Editor: I have a number of concerns about the study by Dr Malenka and colleagues on outcomes following stenting in the bare-metal stent era vs drug-eluting stent era, which concluded that there was a decline in the need for repeat revascularization procedures. First, the authors excluded patients with any percutaneous coronary intervention (PCI) or coronary artery bypass within 1 year. These patients were likely to have bare-metal stents since the drug-eluting stent cohort was from the years immediately after these stents were introduced. Thus, some cases with restenosis within a year were likely to have been left out. Second, the authors did not perform separate analyses for patients receiving bare-metal vs drug-eluting stents even though this information was available based on codes from the International Classification of Diseases, Ninth Revision, Clinical Modification. Third, no information was provided about the reasons certain patients received bare-metal vs drug-eluting stents, which could have led to a selection bias. There was no analysis of differences between patients in each group. It seems likely that patients who had poorer prognosis or contraindications to dual antiplatelet agents preferentially received bare-metal stents. There may also have been a bias induced by physician preferences or hospital policy. Fourth, there is a limited follow-up of only 2 years; this may cover most stent thrombosis but not capture restenosis, which is a more chronic process. In addition, the study interpretation is limited by the absence of angiographic data about the site of a recurrent event, so it is uncertain whether a recurrent event was restenosis, thrombosis, or an unrelated event in another vessel. Fifth, patients with drugeluting stents were using clopidogrel, which itself may lower risk of recurrent myocardial infarction and hence may be a confounder.