Significance of lead aVR in acute coronary syndrome

Table 1 Possible mechanisms of ST-segment elevation or depression in lead aVR and coronary angiographic anatomy in acute coronary syndrome

Lead aVR	Possible mechanisms
ST-segment elevation	Global subendomyocardial ischemia caused by LMT or 3-vessel disease
	Transmural ischemia in the basal portion of the interventricular septum caused by proximal LAD (especially, not-long LAD) occlusion
	Transmural ischemia in the right ventricular outflow tract caused by proximal occlusion of the RCA with a large cornal artery
	Reciprocal changes opposite to ischemic or non-ischemic ST-segment depression in the lateral limb and precordial leads
ST-segment depression	Transmural ischemia in the inferolateral and apical regions caused by occlusion of the long LAD (especially, distal occlusion)
	Transmural ischemia in the inferolateral and apical regions caused by occlusion of the RCA with a large posterolateral branch
	Transmural ischemia in the inferolateral and apical regions caused by occlusion of the LCX (especially, with impaired coronary blood flow of the obtuse marginal or posterolateral branch that perfuses the inferolateral and apical regions)

LMT: Left main trunk; LAD: Left anterior descending coronary artery; RCA: Right coronary artery; LCX: Left circumflex coronary artery.

Table 2 Current evidence concerning the prognostic significance of ST-segment elevation or depression in lead aVR in acute coronary syndrome

Type of ACS	Findings of previous studies
NSTE-ACS	ST-segment elevation in lead aVR was independently associated with increased in-hospital mortality[4]
	Neither minor (0.05-0.1 mV) nor major (> 0.1 mV) ST-segment elevation in lead aVR was an independent predictor of in-hospital or 6-mo mortality[5]
	ST-segment depression ≥ 0.05 mV in any lead plus ST-segment elevation ≥ 0.1 mV in lead aVR was independently associated with increased in-hospital and 1-year cardiovascular deaths[6]
	ST-segment elevation ≥ 0.05 mV in lead aVR was an independent predictor of 90-d adverse outcomes, including death, myocardial infarction, or urgent revascularization[8]
Anterior wall STEMI	U-shaped relationship between ST-segment shift in lead aVR and 30-d mortality was observed[18]
Non-inferior wall STEMI	ST-segment depression ≥ 0.1 mV in lead aVR was independently associated with increased 90-d mortality[19]
Inferior wall STEMI	ST-segment elevation ≥ 0.1 mV in lead aVR was independently associated with increased 30-d mortality[18]
	ST-segment elevation ≥ 0.1 mV in lead aVR was independently associated with increased 90-d mortality[19]

ACS: Acute coronary syndrome; NSTE: Non ST-segment elevation; STEMI: ST-segment elevation myocardial infarction.