ST Elevation in Lead aVR: High-Risk Acute Coronary Syndrome

Primary Clinical Significance

• The American Heart Association suggests that ST elevation in lead aVR, particularly when combined with diffuse ST depression in multiple leads, is associated with severe left main coronary artery disease or proximal left anterior descending artery occlusion, requiring emergent cardiac catheterization 1
• Proximal LAD occlusion above the first septal and diagonal branches produces ST elevation in aVR along with V1-V4, I, and aVL, with reciprocal ST depression in inferior leads II, III, and aVF, as recommended by the American College of Cardiology 1

Pattern Recognition Algorithm

• The European Society of Cardiology recommends measuring ST elevation at the J-point in aVR to quantify the ST elevation, and comparing the magnitude of ST elevation in aVR to V1, with aVR ≥ V1 suggesting LMCA disease 1
• ST elevation greater in aVL than aVR suggests proximal LAD rather than left main, according to the American Heart Association 1
• ST depression greater in lead III than lead II points toward proximal LAD, as indicated by the European Heart Journal 1

Context of Poor R Wave Progression in V3-V6

• Poor R wave progression in leads V3-V6 combined with ST elevation in aVR suggests anterior wall involvement from proximal LAD occlusion, as affected by the basal portion of the left ventricle and interventricular septum, according to the European Heart Journal 1
• Previous anterior myocardial infarction with significant Q waves indicates chronic coronary disease now presenting acutely, as suggested by the European Society of Cardiology 2, 3

Important Caveats

• The European Heart Journal recommends that the ECG should ideally be obtained during symptoms and compared with tracings when symptoms resolve, to accurately diagnose high-risk pathology 2, 3
• A completely normal ECG during chest pain should redirect attention to non-ischemic causes, as indicated by the American College of Cardiology 2, 3
• ST-segment shift and T-wave changes are the most reliable ECG indicators of unstable coronary disease, according to the European Society of Cardiology 2, 3

ST Segment Doming in ECG

Location of ST Segment Doming Based on Affected Vessel

• In proximal LAD occlusion, ST doming appears in leads V1-V4, I, aVL, and often aVR, with the ST-segment spatial vector directed superiorly and to the left, and reciprocal ST depression occurs in leads II, III, aVF, and often V5, according to the American College of Cardiology 4, 5
• In mid-LAD occlusion, ST doming appears in leads V2-V4 and aVL, but not in V1, with the ST-segment vector directed toward aVL, and reciprocal ST depression appears in lead III, as recommended by the American College of Cardiology 4
• In distal LAD occlusion, ST doming appears in leads V3-V6, with less prominent ST elevation in V2 compared to more proximal occlusions, and the ST segment may also be elevated in leads II, III, and aVF due to inferior orientation of the ST vector, according to the American College of Cardiology 4, 5
• In right coronary artery (RCA) occlusion, ST doming appears in leads II, III, and aVF, with greater ST elevation in lead III than in lead II, and often associated with reciprocal ST depression in leads I and aVL, as stated by the American College of Cardiology 4, 6
• In proximal RCA occlusion with right ventricular involvement, ST doming also appears in right-sided chest leads V3R and V4R, and often in V1, with the ST vector directed inferiorly, to the right, and anteriorly, according to the American College of Cardiology 4
• In left circumflex coronary artery (LCx) occlusion, ST doming appears in leads II, III, and aVF, as stated by the American College of Cardiology 4
• ST segment doming should be differentiated from early repolarization, which typically shows concave upward ST elevation, as noted by the American College of Cardiology 7