ORIGINAL ARTICLESThe clinical importance of laboratory-defined aspirin resistance in patients presenting with non-ST elevation acute coronary syndromesAcikel, Sadika; Yildirir, Aylinb; Aydinalp, Alpb; Bal, Ugurb; Kaynar, Gamzeb; Ozin, Bulentb; Muderrisoglu, HaldunbAuthor Information aDepartment of Cardiology, Ministry of Health Dışkapı Yıldırım Beyazıt Research and Educational Hospital, Turkey bDepartment of Cardiology, Baskent University Faculty of Medicine, Ankara, Turkey Received 4 December, 2008 Revised 30 March, 2009 Accepted 31 March, 2009 Correspondence to Dr Sadik Acikel, Ministry of Health Dışkapı Yıldırım Beyazıt Research and Educational Hospital, Department of Cardiology, 06110 Ankara/Turkey Tel: +90 312 5962000; fax: +90 312 3186690; e-mail: firstname.lastname@example.org Blood Coagulation & Fibrinolysis: September 2009 - Volume 20 - Issue 6 - p 427-432 doi: 10.1097/MBC.0b013e32832c87b3 Buy Metrics Abstract In this study, we aimed to assess the factors associated with laboratory-defined aspirin resistance and the relationship of this laboratory-defined aspirin resistance with thrombolysis in myocardial infarction risk score, markers of cardiac necrosis, and inflammatory and thrombotic risk factors in patients with unstable angina or non-ST elevation myocardial infarction. Ninety-seven patients who were under aspirin therapy and hospitalized with unstable angina/non-ST elevation myocardial infarction were included in the study. Laboratory-defined aspirin sensitive and resistant groups were determined by platelet function analyzer; aspirin resistance was defined as collagen/epinephrine closure time less than 165 s. Laboratory-defined aspirin resistance was noted in 29 patients (29.9%), and non-ST elevation myocardial infarction was observed in 46 patients (47.4%). Patients in the group with laboratory-defined aspirin resistance had significantly higher thrombolysis in myocardial infarction risk scores (P < 0.001). When the details of cardiac myonecrosis markers were compared, baseline and follow-up creatine kinase-myocardial band and troponin I values were higher in laboratory-defined aspirin-resistant group. Multivariate analyses revealed that laboratory-defined aspirin resistance was an independent predictor of non-ST elevation myocardial infarction (P = 0.022). Laboratory-defined aspirin resistance is associated with non-ST elevation myocardial infarction, higher markers of cardiac necrosis and thrombolysis in myocardial infarction risk score in patients hospitalized with unstable angina/non-ST elevation myocardial infarction. © 2009 Lippincott Williams & Wilkins, Inc.