Use of Clopidogrel Linked To Lower Risk of Death Or Heart Attack
Heart Attack Risk
For patients with drug-eluting stents who are event-free at six months follow-up (have not had subsequent cardiovascular events or procedures), the extended use of clopidogrel, an "anti-platelet" agent, is associated with a significant reduction in risk for death or heart attack (myocardial infarction) through 24 months after stent implantation, according to a study posted online today by JAMA because of its important findings and in advance of a Food and Drug Administration hearing on the safety of drug-eluting stents scheduled later this week. The study will be published in the January 10, 2007 issue of JAMA.
"Recent studies of drug-eluting intracoronary stents suggest that current antiplatelet regimens may not be sufficient to prevent late stent thrombosis," (a potentially fatal blood clot at the site of the stent), the study authors provide as background information. "Instructions for the use of drug-eluting stents (DES) commercially available in the United States specify treatment with clopidogrel for at least three (for sirolimus coated stents) or six months (for paclitaxel coated stents) after implantation. Premature discontinuation of this minimum antiplatelet therapy has been strongly associated with stent thrombosis."
Eric L. Eisenstein, D.B.A., and colleagues from Duke University Medical Center, Durham, N.C., conducted an observational study of 4,666 patients who underwent initial percutaneous coronary intervention with a bare metal (3,165 patients) or drug-eluting stent (1,501 patients) between Jan. 1, 2000 and July 31, 2005 with follow-up contact at six, 12 and 24 months through Sept. 7, 2006. The researchers used two landmarks in this study: at six and 12 months, the patients were asked if they were taking clopidogrel and if they were event-free (no death, myocardial infarction, or revascularization). Patients who were event-free were divided into one of four groups: drug-eluting stent with clopidogrel (DES + C), DES without clopidogrel (DES - C), bare metal stent with clopidogrel (BMS + C) and BMS without clopidogrel (BMS - C). The authors then determined whether patients had died or had nonfatal myocardial infarction between the landmark time and 24 months follow-up.
Among patients with drug-eluting stents who were event-free at six months (637 with and 579 without clopidogrel), clopidogrel use was a significant predictor of lower rates of death (2.0 percent with vs. 5.3 percent without), and death or myocardial infarction (3.1 percent with vs. 7.2 percent without) at 24 months; however, among patients with bare metal stents (417 with and 1,976 without clopidogrel) there were no differences in death (3.7 percent with vs. 4.5 percent without), or death or myocardial infarction (5.5 percent with vs. 6.0 percent without), the researchers found. Among patients with drug-eluting stents who were event-free at twelve months (252 with and 276 without clopidogrel), clopidogrel use continued to predict lower rates of death (0.0 percent with vs. 3.5 percent without), and death or myocardial infarction (0.0 percent with vs. 4.5 percent without), at 24 months; however, among patients with bare metal stents (346 with and 1,644 without clopidogrel) there continued to be no differences in death (3.3 percent with vs. 2.7 percent without), or death or myocardial infarction (4.7 percent with vs. 3.6 percent without).
"By simultaneously comparing patients in four treatment groups defined by stent type and clopidogrel use, we found that patients with a drug-eluting stent receiving clopidogrel six and twelve months after their initial procedure have significantly lower rates of death and death or MI (myocardial infarction) compared with patients with a drug-eluting stent not receiving this medication," the authors write. "However, the appropriate duration for clopidogrel administration can only be determined within the context of a large-scale randomized clinical trial," the authors conclude.