Supine vs semirecumbent and upright 12-lead electrocardiogram: does change in body position alter the electrocardiographic interpretation for ischemia?

ObjectiveThe goal of this study was to determine if a change in body position alters the 12-lead electrocardiographic (ECG) interpretation for ischemia and ST-segment elevation, the latter having direct implications for initial patient management in the emergency department.MethodsTwelve-lead ECGs were sequentially obtained from a convenience sample of healthy adult volunteers in 3 positions (supine, 0°; inclined, 45°; and upright, 90°). The tracings were randomized, blinded, and then independently read by 2 trained emergency medicine physicians who also assessed for the presence of ischemia and ST-segment elevation myocardial infarction.ResultsSeventy-five subjects were enrolled, with 7 (9%; 95% confidence interval [CI], 4-18) having ischemia on the supine ECG, 9 (12%; 95% CI, 6-22) on the incline, and 9 on the upright tracings. ST-segment elevation myocardial infarction pattern was present on 2 (3%; 95% CI, 0-9) supine, 2 inclined, and 2 upright ECGs.ConclusionsChanges in body position result in some ischemic variations of the 12-lead ECG.