Abstract

Less than half of patients with a chest pain history indicative of acute coronary syndrome havea diagnostic electrocardiogram on initial presentation to the emergency department. Thephysician must dissect the ECG for elusive, but perilous, characteristics that are often missed bymachine analysis. ST depression is interpreted and often suggestive of ischemia; however, whenexclusive to leads V1‒V3 with concomitant tall R waves and upright T waves, a posterior infarctionshould first and foremost be suspected. Likewise, diffuse ST depression with elevation in aVR shouldraise concern for left main- or triple-vessel disease and, as with the aforementioned, these ECGfindings are grounds for acute reperfusion therapy. Even in isolation, certain electrocardiographicfindings can suggest danger. Such is true of the lone T-wave inversion in aVL, known to precedean inferior myocardial infarction. Similarly, something as ordinary as an upright and tall T wave ora biphasic T wave can be the only marker of ischemia. ECG abnormalities, however subtle, shouldgive pause and merit careful inspection since misinterpretation occurs in 20-40% of misdiagnosedmyocardial infarctions.