Compliance as a critical consideration in patients who appear to be resistant to aspirin after healing of myocardial infarction.

The hypothesis that aspirin resistance is often due to noncompliance was investigated. One hundred ninety patients with a history of myocardial infarction were evaluated using arachidonic acid-stimulated light aggregometry at 3 different time points: while receiving their usual daily aspirin, after not receiving aspirin for 7 days, and 2 hours after the observed ingestion of aspirin 325 mg. At the first time point, 17 patients (9%) failed to show aspirin inhibition of platelet aggregation, but 2 hours after observed aspirin ingestion, aspirin inhibition was observed in all but 1 patient.