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Dual Antiplatelet Therapy Tested in High-Risk Stable Patients

The CHARISMA trial tempers hopes that dual therapy might benefit a broad range of high-risk patients.

Dual antiplatelet therapy with aspirin and clopidogrel reduces ischemic events in acute coronary syndrome patients and in patients undergoing angioplasty with stenting. Do the benefits extend to other populations?

In the industry-funded, randomized, double-blind CHARISMA trial, researchers compared a regimen of clopidogrel (75 mg/day) plus low-dose aspirin (75–162 mg/day) with that of placebo plus low-dose aspirin in 15,603 high-risk patients (minimum age, 45; mean age, 64; 70% men). Of the subjects, 78% had documented cardiovascular disease (coronary, cerebrovascular, or symptomatic peripheral arterial disease); nearly all the rest had multiple atherothrombotic risk factors. Median follow-up was 28 months.

Incidence of the primary efficacy endpoint — MI, stroke, or death from cardiovascular causes — was similar in the two groups (dual therapy, 6.8%; aspirin alone, 7.3%). This finding comprised a borderline significant advantage of dual therapy within the subgroup with clinically evident disease (6.9% vs. 7.9%; P=0.046) and a nonsignificant disadvantage in people enrolled because they had multiple risk factors (6.6% vs. 5.5%; P=0.20). Notably, dual therapy conferred significantly higher risks for all-cause and cardiovascular mortality in the multiple risk-factor subgroup, but not in those with clinically evident disease. Overall, severe bleeding was somewhat more common with dual therapy than with aspirin alone (1.7% vs. 1.3%; P=0.09).

Comment: This study does not support extending dual antiplatelet therapy to a broad range of high-risk patients. The authors point to a potential benefit in patients with symptomatic established disease, but as the editorialists note, this hypothesis must first be tested in a trial that focuses more precisely on this population. The CHARISMA data do not trump existing indications for dual antiplatelet therapy (e.g., in unstable patients and patients undergoing coronary stenting). The American Heart Association has issued a statement to help guide patients with questions about the results of the CHARISMA trial.

— Harlan M. Krumholz, MD, SM

Published in Journal Watch Cardiology December 27, 2006

Citation(s):

Bhatt DL et al. for the CHARISMA Investigators. Clopidogrel and aspirin versus aspirin alone for the prevention of atherothrombotic events. N Engl J Med 2006 Apr 20; 354:1706-17.

• Original article (Subscription may be required)
• Medline abstract (Free)

Pfeffer MA and Jarcho JA. The charisma of subgroups and the subgroups of CHARISMA. N Engl J Med 2006 Apr 20; 354:1744-6.

• Original article (Subscription may be required)
• Medline abstract (Free)