Clinical consequences of ST-segment changes caused by body position mimicking transient myocardial ischemia: hazards of ST-segment monitoring?

A case is described in which an acute ST-segment change, presumably due to a change in body position, is erroneously interpreted as an acute ischemic event. Positional ST-segment changes during continuous, multi-lead electrocardiographic (ECG) monitoring are particularly challenging to distinguish from transient myocardial ischemia because 1) positional ECG templates are often not feasible to record at the beginning of monitoring in unstable patients; 2) positional ECG templates, if recorded, are often not readily accessible to clinicians for later comparison; 3) body position cannot be correlated with ST events because patients are out of the direct view of nurses during the event or clinicians review ST trends at a later time; 4) ST monitors typically do not store ECGs frequently enough to be able to observe on the ST trend the gradual ("ramp-like") onset of ST changes that is characteristic of transient ischemia; and 5) absence of chest pain with a ST event does not help clinicians identify false alarms because it is well understood that the majority of ischemic events are clinically silent.