Incidence and Implications of Aspirin Resistance in Patients Suspected to have Acute Coronary Syndrome

Abstract

Background: Patients found to be resistant to aspirin may have increased risk for vascular disease. We studied the clinical significance of aspirin resistance measured by a point-of-care assay in patients who presented with chest pain suspicious of acute coronary syndrome (ACS). Methods: We used the Verify Now Aspirin (Accumetrics) to determine aspirin responsiveness of 314 patients, who were taking aspirin 75–300mg daily for ≥4 weeks, presented to the Emergency Department. Aspirin resistance was defined as an Aspirin Reaction Unit (ARU) ≥550. The endpoints were diagnosis of ACS by serum tropinin-T, major adverse cardiac event at 30 days and 6 months. Test was repeated on patients with aspirin resistance on follow up and a dose of 300mg of aspirin was given to those who were persistently resistant to aspirin. Results:Aspirin resistancewas noted in 30 (9.6%) patients, mean ARU: 598. Patients with aspirin resistance were more likely have history of smoking (63.3% vs. 45.7%, p< 0.05), taking regular NSAID (23.3% vs. 7.5%, p< 0.01) compared to aspirin sensitive patients. There were no diff t s 1 a C c t o r