The accuracy of ST segment deviation in prehospital cardiac monitoring

Elevation or depression of the ST segment of the 12-lead electrocardiogram is an important and established marker of myocardial ischemia or injury. The ST segment deviation in normal individuals using standard cardiac monitoring equipment in the clinical setting of prehospital transport has not been studied. The hypothesis that we tested is that ST segment changes do not occur in normal subjects on standard prehospital cardiac monitors during transport. During a simulated transport, we monitored healthy volunteers of both sexes between the ages of 20 and 30 who had a normal cardiovascular history, physical examination, and 12-lead electrocardiogram. Fourteen of 34 subjects (41%) who qualified as normal exhibited ST segment deviation on the monitor. Of these 14, 11 exhibited ST segment depression, and 3 exhibited ST segment elevation. We conclude that normal individuals can exhibit ST segment deviation on standard prehospital cardiac monitoring equipment during routine transport.