Background There are no controlled prospective studies of the initial electrocardiogram (ECG) in veterans with acute myocardial infarction (AMI).
Purpose To perform a controlled prospective study of presenting ECGs in veterans with AMI.
Method During a 3 month period all patients in a Veterans Affairs Medical Center who had symptoms compatible with AMI and positive biomarkers were prospectively studied for findings on their initial ECG. An experienced ECG reader was provided with the ECGs, which were mixed with tracings from mean age matched controls without AMI. The reader was unaware of the clinical impressions in either group.
Results Of 100 subjects with AMI the initial ECG findings in declining order of frequency for each category were as follows: ST depression = 30%, nonspecific ST-T = 29%, ST elevation = 18%, T wave inversion = 12%, normal = 6% and left bundle branch block = 5%. Of those patients with Q waves, 14 were old or of indeterminate age, whereas new Q waves were observed in 6. There was a significant (p < .001) difference between the frequency of the presenting ECGs for ST depression/nonspecific ST-T vs ST elevation/T wave inversion vs normal/left bundle branch block.
Conclusions In this study group only a minority of subjects had ECG criteria for thrombolytic therapy. Classic AMI findings of new Q wave, ST elevation ± T wave inversion is rare. Either ST segment depression or nonspecific ST-T changes account for a significant majority of cases and the incidence of a completely normal initial ECG is low, approximating one-half of that described in uncontrolled studies.
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