Failure of aspirin to prevent myocardial infarction and adverse outcome during follow-up - a large series of all-comers.

BACKGROUND

Aspirin has been used for secondary prevention of myocardial infarction (MI) in individuals with coronary disease. Although supported by several large controlled trials, aspirin prevents only a portion of recurrent events.

AIM AND METHOD: We set out to study the prevalence of long-term aspirin use prior to admission for MI and its significance for medium-term event-free survival; 998 consecutive patients with acute MI admitted to a tertiary center were included in the study.

RESULTS

Nearly half (42.4%) of all patients reported long-term use of low-dose aspirin prior to the index event. Prior aspirin use was associated with a 50% increase in the risk of both the combined end point of recurrent unstable angina, recurrent myocardial infarction, stroke, or death (OR 1.49; 95% CI 1.12-2.00, P=0.006) and mortality (OR 1.50; 95% CI 1.03-2.17, P=0.03) during 10-month follow-up. Prior aspirin use was not associated with an increased frequency of added antithrombotic therapy at discharge.

CONCLUSIONS

We have found that prior aspirin use is common in patients hospitalized for acute MI. Individuals already on aspirin had increased risk of recurrent ischemic events and all-cause mortality during the 10-month follow-up after their index MI.