What does a positive ECG (electrocardiogram) lead AVR (augmented vector right) indicate?

Positive ECG Lead aVR: Clinical Significance

Primary Interpretation

A positive QRS complex in lead aVR is abnormal and should immediately raise suspicion for either dextrocardia/cardiac malrotation or limb lead misplacement, as this lead normally shows a predominantly negative deflection. 1

Normal Lead aVR Characteristics

• Lead aVR views the heart from the right shoulder, with its positive electrode on the right arm, and normally displays a predominantly negative P-QRS-T complex because the main electrical vectors of the heart point away from this lead 2
• The negative deflection in aVR is expected because cardiac depolarization moves from right to left and superior to inferior, directly opposite to aVR's orientation 3

Diagnostic Significance of Abnormal aVR Findings

Lead Misplacement vs. Cardiac Malposition

• When a positive QRS appears in aVR, immediately verify proper lead placement before pursuing further workup 1
• Limb lead reversal (particularly right and left arm electrodes) is the most common cause of a positive aVR complex and can be quickly corrected by repeating the ECG with proper electrode placement 1
• If lead placement is confirmed correct, consider dextrocardia or other congenital cardiac malrotations 1

ST Elevation in aVR During Acute Coronary Syndrome

ST elevation in aVR (≥0.5-1 mm) combined with widespread ST depression in other leads indicates severe coronary disease, particularly left main or proximal left anterior descending artery occlusion, and represents a STEMI-equivalent requiring emergent cardiac catheterization. 3, 4

Key features include:

• ST elevation in aVR ≥0.5-1 mm with concurrent ST depression in 8 or more leads suggests left main coronary artery disease or severe three-vessel disease 3, 4
• This pattern (the "aVR sign") carries high mortality risk and should prompt immediate reperfusion therapy 4
• ST elevation in aVR combined with ST elevation in V1-V4, I, and aVL indicates proximal LAD occlusion involving the basal interventricular septum 2

Exercise Testing Context

• During exercise stress testing, ST elevation in standard lead aVR (equivalent to ST depression in inverted -aVR) may indicate demand ischemia and has been associated with left main or proximal LAD stenosis 3
• The inverted aVR (-aVR) is endorsed for routine use and aligns with the left ventricular axis, making it sensitive for detecting subendocardial ischemia 3

Clinical Pitfalls and Caveats

Common Errors to Avoid

• Never dismiss aVR as an "unimportant" lead—it provides critical diagnostic information that other leads cannot offer 5
• Do not assume ST elevation in aVR automatically indicates left main disease; other high-risk conditions (severe three-vessel disease, diffuse subendocardial ischemia) can produce similar patterns 4
• Avoid unnecessary interventions by first confirming proper lead placement when encountering an unexpectedly positive aVR complex 1

Additional Diagnostic Uses of aVR

Lead aVR also helps identify:

• Brugada syndrome (Type 1 pattern with ST elevation) 3, 5
• Pericarditis 5
• Ectopic atrial rhythms 5
• Fascicular blocks 5

Practical Algorithm for Positive aVR

1. First step: Verify proper limb lead placement—repeat ECG if uncertain 1
2. If leads confirmed correct and positive QRS persists: Consider imaging for dextrocardia/cardiac malposition 1
3. If ST elevation in aVR with chest pain: Assess for widespread ST depression in other leads 3, 4
   • If present: Treat as STEMI-equivalent, activate catheterization lab emergently 3, 4
   • Obtain echocardiography and troponins immediately 3
4. During exercise testing: ST elevation in aVR suggests high-grade proximal coronary stenosis requiring coronary angiography 3