<qa>  What is best defined as an ineffective inhibition of the platelet cyclooxygenaAcetylsalicylic acid ASA resistance R is best defined as an ineffective inhibition of the platelet cyclooxygenase COX-1 pathway, and has been reported in 1 to 61 of patients treated with ASA. Impaired response to ASA has been associated with an increased risk of ischemic events in patients with known coronary artery disease. We sought to investigate the incidence of ASA-R in clinical practice. 