"Nonspecific" ST and T-Wave Changes
A study was made of 1,000 consecutive adult in-patient electrocardiograms to determine the possibility of making a more precise diagnosis than "nonspecific ST and T-wave changes." More than 50 per cent (209) of the 410 abnormal electrocardiograms (exclusive of arrhythmias) were characterized by nonspecific depression of ST segment or T wave inversion, or both.
These 209 cases comprised four groups: (1) 46 patients (22 per cent) had received digitalis, which could account for the ST-T changes; (2) 57 patients (27 per cent) had had an acute episode of cardiac pain within 5 days prior to the electrocardiogram; (3) 57 patients (27 per cent) had had no recent cardiac pain but suffered from some disease that could be regarded as a possible cause for the ST-T changes; and (4) 49 patients (24 per cent) had no apparent cause for the electrocardiographic changes. In the last group, in contrast with the others, the ST-segment depression was less than 0.5 mm. and the T-wave inversion less than 1 mm.
In patients with recent cardiac pain, as contrasted with those without such pain, the electrocardiograms were characterized by a combination of ST depression and T-wave inversion, with a depth of more than ½ mm. of the ST depression and more than 1 mm. inversion of the T wave, by isolated T-wave inversion of more than 2 mm. and especially by more than 5 mm. in the midprecordial leads, and by an ischemic contour of the ST segment that is depressed more than ½ mm.
There was no definite difference in the electrocardiographic findings in the patients with recent cardiac pain of less than ½ hour and those with recent cardiac pain of more than ½ hour when the cases with transmural infarction (Q-wave changes) were excluded. This is compatible with the concept that the electrocardiogram usually does not distinguish between subendoeardial ischemia and subendocardial necrosis. The latter differentiation would depend on multiple clinical and laboratory findings.
- © 1961 American Heart Association, Inc.