Electrocardiographic and enzymatic findings in acute non-Q wave myocardial infarction. Results from the Multicenter Diltiazem Reinfarction Study

W. E. Boden, R. E. Kleiger, R. S. Gibson, D. J. Schwartz, R. J. Capone, K. B. Schechtman, P. M. Young, B. J. Geiger, R. Roberts

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Abstract

In spite of the apparent rising prevalence of non-Q wave myocardial infarction (MI), and the widespread applicability of cardiac enzymes in the diagnosis of myocardial necrosis, all prior published studies have required obligatory ST segment shifts and/or T wave inversion in the diagnosis of non-Q wave MI. Accordingly, the frequency of clinically and enzymatically defined non-Q wave MI without indicative electrocardiogram (ECG) changes has never been assessed, nor has a systematic analysis of serial ECGs and cardiac enzymes been undertaken in a large prospective non-Q wave MI population. We utilized the extensive data base created from the Diltiazem Reinfarction Study of MB-creatine kinase (CK)-confirmed non-Q wave MI, which was a multicenter study of the effect of diltiazem therapy on early reinfarction. Five hundred and seventy-six patients underwent serial ECG analyses on admission, study day 2, study day 3 and at predischarge (10 ± 2 days after trial entry). A total of 2,304 ECGs were analyzed by 5 blinded investigators, and tracings were examined for the presence or absence of definable ST-T wave changes in 2 or more leads within 3 ECG lead groups: anterior = V1 - V4; inferior = II, II, aVF; lateral = I, aVL, V5 - V6; combination location = 2 or more lead groups; nonlocalizable = no diagnostic ST or T wave abnormalities. CK and MB-CK values were measured at 12-hour intervals throughout the 14-day study period. At study entry, 32 patients (5.5%) were found, in retrospect, to have had acute Q wave MI at entry, 439 of the remaining 544 patients (81%) had localizable ECG changes and 105 (19%) did not. Combination location (≥2 lead groups) non-Q wave MI was the most prevalent (48%), followed by lateral location (18%), anterior location (14%) and inferior location (8%). ST segment elevation was noted in 187/544 patients (34%) on the admission ECG, but in only 37 patients (20%) did Q waves develop subsequently. Of note, mean peak CK values were not significantly different among subgroups, and the highest mean CK values were observed in patients with nonlocalizable non-Q wave MI (668 ± 877 vs. 616 ± 26 IU for the remaining localizable subgroups; p = NS). We noted further that 76 of 544 patients (14%) progressed to Q wave MI during the 14-day observation period, and 67 patients (12%) 'normalized' their ECGs prior to discharge. Thus, the early ECG findings of non-Q wave MI are most frequently global, less commonly isolated to a single ECG lead group, are attended by a high prevalence of initial ST segment elevation, and are nonlocalizable in almost 20% of patients.

Original languageEnglish
Pages (from-to)125-133
Number of pages9
JournalAmerican Journal of Noninvasive Cardiology
Volume2
Issue number3
DOIs
StatePublished - Jan 1 1988

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