[The diagnostic and prognostic value of the 12-lead electrocardiogram in assessing the severity of coronary disease in the acute phase of an acute myocardial infarct].

UNLABELLED

The conventional twelve-lead electrocardiogram (ECG) still is the cheapest, most used and absolutely essential diagnostic method for the acute phase of myocardial infarction (MI) allowing risk stratification and coronary prognostic evaluation in this phase mainly by the localization of the ST segment depression and/or T wave inversion (ST/T changes) not related to the infarct area in Q-Wave MI or at any localization in case of non-Q wave MI. The etiology and pathophysiology of these ST/T changes in the setting of MI has been controversial. With the objective of determining ECG prognostic and diagnostic value, 70 patients (Pts) (59 men and 11 women, mean age 58 + 13) admitted in the acute phase of MI were studied with revision of acute phase ECG ST/T changes. All patients underwent coronary angiography and ventriculography at the moment of hospital discharge. Patients were divided into two classifications: A) MI localization: A1--Q-wave MI (anterior--20 pts, inferior--29 pts, lateral--1 pt); A2--non-Q wave--20 pts. B) Evidence of ST/T changes outside the infarct area in Q wave MI or at any localization in non-Q wave MI (group B1--with ST/T changes, group B2--without ST/T changes). We correlated the angiographically documented coronary artery disease in groups with ST/T changes and their localization.

RESULTS

A1) Anterior MI group: in the 6 pts (30%) with "opposite" (inferior) ST/T changes, right coronary artery (RCA) disease was documented in 5 and in the other 14 patients the RCA did not show significant lesions. Inferior MI group: in the 24 Pts (83%) with "opposite" (precordial) ST/T changes. 23 of them had angiographic correlation (left anterior descending (LAD) and/or circumflex (CX) artery disease). Lateral MI group: one Pt with anterior wall ST/T changes and LAD and CX disease. A2) Non-Q wave group: in 13 pts (87%) the diseased vessels were correlated with the site of ST/T changes. B1) Q-Wave AMI: left main and 3-vessel disease in 2 pts, 3-vessel disease in 17 pts, 2-vessel disease in 9 pts, 1-vessel disease in 2 pts and non-significant disease in one pt. Non-Q wave MI: left main and 3-vessel disease in 1 pt, 3-vessel disease in 7 patients, 2-vessel disease in 3 pts and 1-vessel disease in 4 pts. B2) non-Q Wave MI: 3-vessel disease in 5 pts, 2-vessel disease in 7 pts, 1-vessel disease in 6 pts and non-significant disease in 1 pt. Non-Q wave MI: 2-vessel disease in 2 pts and non-significant disease in 1 pt.

IN CONCLUSION

When pts were divided according to MI localization, a correlation was found between the ST/T changes outside the infarct area with CAD in 91% of Pts in the Q-Wave infarction group, with more significance in inferior and lateral MI. In the non-Q wave group, we found correlation between the a coronary lesions and the localization of ST/T changes in 87% of the pts. The pt group with ST/T changes presented, when compared with the pt group without these changes, evidence of more severe coronary artery disease (CAD): 3 vessels or left main with 3 vessel disease. However, only in the Q-Wave infarction group was a statistically significant difference found between the group with ST/T changes compared to the group without these changes, concerning to the existence of more severe coronary disease.