[Role of the electrocardiogram in detecting transient myocardial ischemia]

Electrocardiographic evaluation of transient myocardial ischemia has three categories: detection, localization and severity, and prognostic evaluation. For the first category, the resting 12 leads electrocardiograms (RECG) were compared to those obtained by Holter monitoring (DECG) regarding ST segment changes. In 21% of patients with chest pain and normal RECGs, transient ST changes were disclosed by DECG. In 22% of patients with chest tightness or precordial discomfort and normal RECG, ST changes were disclosed by DECG. With onset of chest pain DECG showed ST changes in 56% of patients, and with tightness of the chest or precordial discomfort 35% of patients had DECG abnormalities. When DECG showed ST depression, cardiac complaints were accompanied in 25%, and when ST elevation occurred, they were accompanied in 45%. During maximal exercise test, ST changes appeared in all cases who complained chest pain. On the contrary, however, 48% of the patients complained chest pain at the time of the appearance of ST change. ST changes were examined in asymptomatic healthy persons. DECG showed ST changes in 17-25% in young persons. In the middle age persons, these were recognized from 15 to 35%. By treadmill exercise, young age group showed no changes in ST, whereas the middle age group showed the change in 4-8%. As to the localization, severity, and prognostic evaluation, the literatures were reviewed.