The combination of dual antiplatelet therapy with clopidogrel and low-dose aspirin did not show any significant benefit in patients with symptomatic atherothrombosis, according to a study published in the New England Journal of Medicine. The trial was coordinated by the Cleveland Clinic Cardiovascular Coordinating Center.

Atherothrombosis occurs when a blood clot forms on fatty deposits -- atheromas -- in the wall of a blood vessel. If the clot grows until it completely blocks an affected artery, this can result in life-threatening consequences such as heart attack and stroke.

In the study, researchers randomly assigned 15,603 patients with either clinically evident cardiovascular disease or multiple risk factors to receive clopidogrel plus low-dose aspirin or placebo plus low-dose aspirin, and followed them for a median of 28 months. The primary efficacy end point was a composite of myocardial infarction, stroke, or death from cardiovascular causes.

The rate of the primary efficacy end point was 6.8 percent in the clopidogrel-plus-aspirin group and 7.3 percent in the placebo-plus-aspirin group, the study found. The respective rate of the principal secondary efficacy endpoint -- which included hospitalizations for ischemic events -- was 16.7 percent and 17.9 percent, respectively.

Overall, the study found, clopidogrel plus aspirin was not significantly more effective than aspirin alone in reducing the rate of myocardial infarction, stroke, or death from cardiovascular causes. There was a slight suggestion of harm in patients with multiple risk factors, the study noted.