Bleeding risk post-MI increased with number of antithrombotic drugs

The risk for hospitalization due to bleeding in patients who have had a myocardial infarction increased with the increasing number of antithrombotic drugs patients were assigned, according to data from a Denmark patient registry.

In addition, those patients who had non-fatal bleeding were more likely to have a repeat MI or die than those without non-fatal bleeding.

Researchers identified 40,812 patients aged 30 or older who had been admitted to the hospital after first MI. Patients were than categorized according to antithrombotic prescriptions: aspirin alone, clopidogrel alone, or vitamin K antagonist alone; dual therapy with aspirin plus clopidogrel, aspirin plus vitamin K antagonist or clopidogrel plus vitamin K antagonist; or triple therapy.

Mean follow-up was 476.5 days. During that time, 4.6% of patients were admitted to the hospital for a bleeding event.

Incidence of bleeding increased with the number of drugs being taken. Overall annual bleeding incidence was 2.6% for aspirin alone, 4.6% for clopidogrel alone, 4.3% for vitamin K antagonist alone, 3.7% for aspirin plus clopidogrel, 5.1% for aspirin plus vitamin K antagonist, 12.3% for clopidogrel plus vitamin K antagonist, and 12% for triple therapy.

his translates into an increased risk of bleeding of 1.3 for clopidogrel, 1.2 for vitamin K antagonist, 1.5 for aspirin plus clopidogrel, 1.8 for aspirin plus vitamin K antagonist, 3.5 for clopidogrel plus vitamin K antagonist, and 4.1 for triple therapy.

Finally, 37.9% of patients with non-fatal bleeding went on to have a recurrent MI or died vs. 18.4% of patients who were not hospitalized for a non-fatal bleed (P<.0001).

In an accompanying editorial, Erik L. Grove, MD, of Aarhus University Hospital, Skejby, Denmark, and Robert F. Storey, MD, of University of Sheffield, U.K., wrote, “The findings of Sorenson and colleagues suggest that a greater awareness of the prognostic importance of bleeding is warranted; they also underline the need for careful selection of antithrombotic drug combinations according to individual patient’s characteristics.”

Sorensen R. Lancet. 2009;374:1967-1974.