Variations in the electrocardiograms of young adults: are revised criteria for thrombolysis needed?

Abstract

The evaluation of chest pain in young adults has changed with the recognition of cocaine-induced myocardial ischemia. The high frequency of abnormal electrocardiograms (56-84%) in the cocaine-user population is largely due to "normal" electrocardiographic variants (early repolarization). The authors sought to determine the frequency of these "normal" variants in a young population, and whether these findings can be confused with acute ischemia. A prospective convenience sample of subjects aged 18 to 35 without known heart disease was interviewed and had 12-lead electrocardiographic tracings performed. An emergency physician (physician 1) and a cardiologist (physician 2) read the tracings while blinded to patient history, age, and race. When the physicians disagreed, another physician adjudicated the diagnosis. Four hundred fourteen subjects (127 black, 175 Hispanic, and 112 Caucasian) were enrolled. Overall, 154 tracings (37%) were normal, 245 (59%) were abnormal but nondiagnostic for ischemia, and 15 (4%) were consistent with ischemia. Frequencies of repolarization "abnormalities" as determined by physicians 1 and 2, respectively, were: blacks, 32%, 51%; Hispanics, 26%, 35%; Caucasians, 17%, 27%; chi-squared, p = 0.02 and 0.0004. Patients with ischemic electrocardiograms according to physician 1 had a high frequency of repolarization "abnormalities" according to physician 2, and vice versa (100%, 61%). Electrocardiographic criteria for thrombolytic use per physician 2 were present in 31 patients (7%): blacks, 9%; Hispanics, 10%; and Caucasians, 2%; chi-squared, p = 0.03.