PREDICTORS OF NON-Q-WAVE ACUTE MYOCARDIAL-INFARCTION IN PATIENTS WITHACUTE ISCHEMIC SYNDROMES - AN ANALYSIS FROM THE THROMBOLYSIS IN MYOCARDIAL-ISCHEMIA (TIMI)-III TRIALS

Among patients with acute ischemic syndromes, patients with non-Q-wave acute myocardial infarction (AMI) are known to be at higher risk for death, reinfarction, and other morbidity than those with unstable angi na. The aim of this study was to develop a clinically useful predictio n rule to assist in distinguishing, at the time of presentation, patie nts with non-Q-wave AMI from those with unstable angina. The TIMI IIIB trial enrolled 1,473 patients presenting with ischemic pain at rest w ithin 24 hours who had either electrocardiographic changes or document ed coronary artery disease. Non-Q-wave AMI on presentation was documen ted by elevation of creatine kinase-MB in 33% of patients. Fifty clini cal and electrocardiographic variables were compared between the patie nts with non-Q-wave AMI and unstable angina. After performing logistic regression, 4 baseline characteristics independently predicted non-Q- wave myocardial AMI: the absence of prior coronary angioplasty (odds r atio [OR] = 3.3, p <0.001), duration of pain greater than or equal to 60 minutes (OR = 2.9, p <0.001), ST-segment deviation on the qualifyin g electrocardiogram (OR = 2.0, p <0.001), and recent-onset angina (OR = 1.7, p = 0.002). Using these 4 characteristics, a prediction rule fo r non-Q-wave AMI was developed. For the entire cohort of patients in T IMI III, the percentages of patients with non-Q-wave AMI when 0, 1, 2, 3, and 4 risk factors were present were 7.0%,;19.6%, 24.4%, 49.9%, an d 70.6%, respectively (p <0.001). Thus, easily identifiable characteri stics at presentation can be used to assess the likelihood of non-Q-wa ve AMI.