Clopidogrel increases bleeding risk in cardiac patients with drug-eluting stents
Research Activities, November 2010, No. 363
Patients suffering from a blockage in their coronary arteries usually undergo coronary angioplasty. In this procedure, a balloon-tipped catheter is inserted through the groin into the blocked artery along with a drug-eluting stent (wire mesh tube), which expands when the balloon is inflated to provide a scaffold to keep the coronary artery open. The stent remains once the balloon catheter is withdrawn. After this procedure, patients may be placed on clopidogrel, a blood-thinning agent, to prevent clots from forming on the stent. However, a new study finds that patients placed on clopidogrel have an increased risk of bleeding, although their risk for a heart attack decreases.
A total of 7,689 patients were evaluated for this study. All had received drug-eluting stents, with just under half (49.1 percent) receiving clopidogrel for more than 6 months. Patients were followed for up to 18 months for signs of major bleeding, a heart attack, or death. Particular attention was paid to the time interval from 0 to 6 months, the recommended time for clopidogrel therapy from the drug's manufacturer. After a mean follow-up of 418 days, 3.6 percent of patients experienced a major bleeding event. The percentage of patients who suffered a heart attack or died was 3.7 percent and 2.9 percent, respectively. Even when the researchers adjusted for various factors, there was still a significant association between clopidogrel and an increase in major bleeding for all time intervals. These included 0 to 6 months, 7 to 12 months, and 13 to 18 months. However, patients on clopidogrel had a decreased risk of having a heart attack for all time intervals while on the therapy. There was also a decrease in death rate for clopidogrel patients during the 7- to 12-month time interval.
The researchers call for more randomized clinical trials to determine the optimal time patients should be on clopidogrel in order to reduce bleeding risks and increase the benefits of therapy. The study was supported in part by the Agency for Healthcare Research and Quality (HS00331).
See "Increased risk of bleeding in patients on clopidogrel therapy after drug-eluting stents implantation," by Thomas T. Tsai, M.D., M.Sc., P. Michael Ho, M.D., Ph.D., Stanley Xu, Ph.D., and others in the June 2010 Circulation Cardiovascular Interventions 3, pp. 230-235.