Thrombosis in Coronary Drug-Eluting Stents

Abstract

Coronary drug-eluting stents (DES) were first approved for use in the United States in 2003 (Cypher Coronary Sirolimus-Eluting Stent [SES], Cordis Corporation, Miami Lakes, Fla) and 2004 (Taxus Express Paclitaxel-Eluting Stent [PES], Boston Scientific Corporation, Natick, Mass) on the basis of randomized, blinded, controlled studies that demonstrated reduced target vessel failure (Cypher) and target vessel revascularization (TVR) (Taxus) at 9 months. Major adverse cardiac events were also significantly reduced for both DES when compared with bare metal stents (BMS). Presentations at national and international meetings in 2006 suggested that DES use may be associated with an increase in late (≥1 year after implantation) stent thrombosis (ST). Other studies suggested that there may be a significant increase in the combined end point of death and myocardial infarction (MI) compared with BMS. In response to these safety concerns, the US Food and Drug Administration (FDA) convened a meeting of the Circulatory System Medical Devices Advisory Panel. Advisory Panels make nonbinding recommendations to the FDA. Panelists recognized the need for a method to assess the true frequency of ST. However, one of the challenges in the assessment of DES ST risk is that the ST definition varies from study to study (Table 1). Differences in these on-protocol definitions of ST make it difficult to pool studies for analysis and to compare one stent to another (sirolimus-eluting versus paclitaxel-eluting). Furthermore, it is important to note that the on-protocol definition of ST for some of the clinical trials that support DES approval in the United States censored events that occurred after target lesion and/or target vessel revascularization (TLR/TVR). This means that an ST that occurs after TLR/TVR may not be counted as an ST by the on-protocol definition. Because BMS patients are more likely to experience restenosis and TLR/TVR than DES patients, more BMS patients …