ECG Review
By Ken Grauer, MD
Chest Pain and an Anterior Culprit’
Figure — ECG from a patient with new-onset chest pain.
Scenario: The ECG in the Figure was obtained from a patient with new-onset chest pain. What is the likely "culprit" artery? Is this patient a good candidate for acute reperfusion?
Interpretation: The rhythm is sinus at about 60/minute. There is an obvious acute ST-elevation myocardial infarction (STEMI) in progress — with marked ST elevation across the precordial leads. The shape of this ST elevation is coved (convex-down), in association with "hyperacute" (broad and peaked) T waves. Factors suggesting that this patient is an ideal candidate for acute reperfusion include: 1) large extent of anterior involvement with marked ST elevation in multiple leads; 2) new-onset chest pain by history, in association with reciprocal inferior ST depression — both suggesting an early stage in evolution; and 3) no precordial lead Q waves have yet formed.
STEMIs are almost always associated with acute occlusion of a major coronary artery — called the "culprit" artery. Evaluation of the initial ECG obtained at the onset of chest pain may provide insight to the probable site of acute occlusion. Awareness of where to look facilitates the angiographer’s task during cardiac catheterization, which may expedite angioplasty and stent placement if acute reperfusion is attempted. Exclusive ST elevation in an anterolateral lead distribution (leads V1-through-V5 in the Figure) localizes the occlusion to the left coronary system.
There are several reasons why the "culprit" lesion in this case is unlikely to be the left main coronary artery. First, acute occlusion of the left main is rarely seen in practice, because this lesion most often leads to rapid demise of the patient. In addition, ST elevation is usually prominent in lead aVR with left main occlusion, whereas no more than minimal ST elevation is seen in lead aVR in the Figure.
Instead, the "culprit" lesion in this case is most likely to be at a proximal site in the left anterior descending (LAD) coronary artery. Factors in favor of a proximal LAD location include: 1) ST elevation that is most marked in leads V2-through-V4; 2) prominent ST elevation already in lead V1 compared to no more than minimal ST elevation in lead aVR; and 3) reciprocal ST depression in the inferior leads.
A more distal site of occlusion in the LAD is less likely in this case because: 1) more distal LAD occlusions rarely manifest such prominent ST elevation in lead V1 and V2, and 2) reciprocal ST depression may be absent in the inferior leads with more distal LAD occlusion, and some inferior ST depression is seen here.
