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lt ve characteristics, and clinical significance of transient ST segment elevation in patients with acute coronary syn-dromes. Methods A secondary analysis from two prospective studies utilizing 12-lead ST segment monitoring was used to compare ST elevation vs ST depression events. Conclusions Transient ST elevation is nearly as prevalent as transient ST depression in patients with acute coronary syndromes. Since the vast majority of ST events are brief and otherwise clinically silent, ST segment monitoring is more efficacious in detecting ischaemic events and in pre-producing severe myocardial ischaemia that is typically associated with chest pain. Although ST elevation is patients with acute coronary syndromes apart from a vasospastic mechanism[3]. These experts propose that theknown to occur transiently in vasospastic, or ‘variant’ angina[1], and, on rare occasions, during exercise test-ing[2], it is more commonly encountered as the more persistent ‘injury ’ pattern associated with evolving acute underlying pathophysiology of transient ST segment elevation in acute coronary syndromes is related to platelet aggregation and subsequent mural thrombus formation which can lead to transient complete coronary occlusion. While undertaking a study to determine the value of continuous 12-lead ST segment monitoring of patients hospitalized with acute coronary syndromes, we were impressed by how often we were seeing brief episodes of major ST segment elevation (Fig. 1). Therefore, the purpose of this analysis was to determine: (1) how ofte