The established electrocardiographic classification of anterior wall myocardial infarction misguides clinicians in terms of infarct location, extent and prognosis

Abstract

Background:The currently used scheme for the classification of infarct location and extent in anterior myocardial infarction (MI) is intuitive rather than being evidencebased, and recent evidence suggests that it may be misleading both in anatomic and prognostic sense. Material and Methods:Consecutive patients with the diagnosis of anterior MI were enrolled. All electrocardiograms (ECG) were first classified according to established scheme and then reassessed using newer criteria for angiographic site of occlusion.The site of left anterior descending (LAD) occlusion was determined using multiple angiographic views. Clinic, echocardiographic and angiographic outcomes were compared.Results: A total of 379 anterior MI cases were enrolled, final study population consisted of 267 patients. The established scheme did not predict infarct size or adverse outcomes. Location of the myocardium subtended by the occluded coronary network did not match with the anatomic location as ECG classification implies. Many high-risk patients with proximal LAD were classified as "anteroseptal", whereas the majority of the patients labeled as "extensive anterior MI" had in fact distal occlusions. On the other hand, expert interpretation was fairly accurate in predicting adverse outcomes and the site of angiographic involvement. Conclusion:Classifying patients according to the established scheme neither gives prognostic information nor accurately localizes infarction. It should be regarded as obsolete and its use should be abandoned. Instead, the extent of infarction can be inferred from newer criteria provided by the angiographic correlation studies.

Where Is the Culprit Lesion in the New Electrocardiogram Pattern?

“…The primary determinant of the lead numbers and locations that demonstrated STE was the injury vector's spatial orientation. 5 Different ischemic scenarios produce ST vectors at different orientations in the frontal plane. The ST vector of subendocardial ischemia caused by subtotal occlusion of the LMCA was probably directed to lead aVR, while that of acute inferior MI caused by RCA occlusion was probably directed to lead III.…”

Acute Coronary Syndrome with ST Segment Elevation: New Electrocardiographic Pattern

“…Theoretically, the average ST-vector that is more rightward than usual can be explained by the summation of the ST-vector of inferior MI and the ST-vector of subendocardial ischemia caused by the concurrent critical vessel disease. [1][2][3][4] Not many descriptions of this new ST equivalent pattern are found in the literature. Evaluating these findings in the future would indicate the real incidence.…”

Where Is the Culprit Lesion in the New Electrocardiogram Pattern?

“…3 However, studies have revealed that the locations of the leads demonstrating STE do not reliably indicate the location of the infarcted myocardium. 4,5 Furthermore, the requirement of the presence of STE in 2 or more contiguous leads reduces the sensitivity of ECG for diagnosing STEMI in some configurations. Therefore, the current guideline-recommended STE criteria for myocardial infarction is far from optimal.…”

“…Others have proposed other causal explanations, ranging from well-intentioned to less so. [4][5][6] All of these factors may be plausible.…”