From the Guidelines
Lead aVR positivity on an electrocardiogram (ECG) is most commonly caused by inferior wall myocardial infarction, particularly when the right coronary artery (RCA) is occluded, as well as left main and proximal left anterior descending stenoses 1.
Causes of Lead aVR Positivity
- Inferior wall myocardial infarction: Occlusion of the RCA or left circumflex coronary artery (LCx) can cause ST-segment elevation in leads II, III, and aVF, and reciprocal ST-segment depression in leads I and aVL, which may be associated with ST-segment elevation in lead aVR 1.
- Left main and proximal left anterior descending stenoses: ST-segment deviation in lead aVR can be a useful finding in detecting demand ischemia during exercise and recognizing left main and proximal left anterior descending stenoses 1.
- Sodium channel blocker poisoning: Characteristic ECG changes, including intraventricular conduction delay and terminal rightward axis deviation, best appreciated in lead aVR, can occur in patients with sodium channel blocker poisoning 1.
- Subendocardial ischemia: ST-segment deviation in lead aVR can also be caused by subendocardial ischemia, which may show up as ST elevation in standard-lead aVR 1.
Clinical Implications
It is essential to consider the spatial orientation of the ST-segment vector in both the frontal and transverse planes when interpreting lead aVR positivity, as the magnitude of ST-segment elevation and reciprocal ST-segment depression may not be identical due to differences in lead placement and distance from the ischemic region 1.
From the Research
Causes of Lead aVR Positivity
The causes of lead aVR positivity on an electrocardiogram (ECG) can be attributed to various conditions, including:
- Congenital heart malrotation or lead misplacement, as a positive P-QRS complex in the aVR lead should raise prompt suspicion for these conditions 2
- Severe left main coronary artery stenosis or diffuse coronary artery disease, as the combination of multilead ST depression and ST elevation in lead aVR has been associated with a high risk of death 3
- Acute coronary syndrome (ACS), as ST elevation in lead aVR can be suggestive of left main coronary artery occlusion 4
- Acute pericarditis, as PR-segment elevation in lead aVR can be indicative of this condition 4
- Tricyclic antidepressant poisoning, as a prominent R wave in lead aVR can be suggestive of significant poisoning 4
- Wolff-Parkinson-White syndrome, as ST-segment elevation in narrow complex tachycardia can be indicative of this condition 4
- Other conditions such as pericarditis, Brugada syndrome, fascicular blocks of the right branch, and ectopic left atrial rhythms, as lead aVR can be sensitive in locating obstructed epicardial coronary arteries and recognizing these conditions 5
Clinical Significance
Lead aVR can provide valuable information in the diagnosis and prognosis of various cardiovascular conditions, including myocardial infarction, myocardial ischemia, conduction disturbances, supraventricular arrhythmias, acute pericarditis, and pulmonary emboli 6. Careful attention to lead aVR, as well as the other 11 leads of the standard electrocardiogram, can be rewarding to physicians caring for patients with cardiovascular disease. The aVR sign, which combines multilead ST depression and ST elevation in lead aVR, has been associated with severe left main coronary artery stenosis or diffuse coronary artery disease and a high risk of death, and may represent an ST-elevation myocardial infarction (STEMI) equivalent 3.