Lead aVR: The Forgotten 12th Lead
Augmented leads (aVR, aVF, and aVL) were developed to derive more localized information looking at the right, lower, and left part of the heart respectively. Specifically, lead aVR obtains information from the right upper side of the heart. It also gives reciprocal information on the left lateral side of the heart, which is already covered by leads aVL, I, II, V5, and V6. This is the main reason lead aVR has become forgotten.
What is the sensitivity and specificity of lead aVR for left main coronary artery (LMCA) occlusion?
|aVR ST elevation (>0.05 mV) greater than
V1 ST elevation 1
|aVR ST elevation (>0.05 mV) 2||68.2%||73.3%|
|aVR ST elevation (>0.05 mV) 3||91%||79%|
|aVR ST elevation (>0.1 mV) 3||80%||93%|
|aVR ST elevation (>0.15mV) 3||27%||98%|
Conclusion: ST elevation >0.05 mV in aVR has a SENSITIVITY 68-91% and SPECIFICITY 73-80%.
Does ST elevation in lead aVR predict clinical outcome?
- ST elevation of aVR (0.15 mV) predicts death with 75% sensitivity and 75% specificity 1
- ST elevation of aVR (0.05 – 0.1 mV) associated with death 8.6%
- ST elevation of aVR (>0.1 mV) associated with death 19.4% (1.3% with no aVR ST elevation) 4
- MORTALITY in ST elevation of aVR (0.05 mV) 30.2% vs no ST elevation in aVR 12.2% 5
Conclusion: ST elevation in lead aVR has INCREASED MORTALITY versus no ST elevation in lead aVR.
What is the best management of ST elevation in lead aVR?
- Several studies quote a 3-year mortality rate of 50% for medical management and 36% for PCI, stating that surgery (CABG) is the treatment of choice.
- There are several new studies now looking at drug eluding stents (DES) as an option:
- Currently the EXCEL (Evaluation of Xience Prime versus Coronary Artery Bypass Surgery for Effectiveness of Left Main Revascularization) trial is underway and recruiting patients and can hopefully give us a more clear answer.
Conclusion: It is still not clear who would be best treated with PCI versus CABG in LMCA occlusion.
Lead aVR is a forgotten but valuable lead that is highly predictive of LMCA occlusion and gives prognostic information. The best management of LMCA occlusion is still unclear (PCI vs CABG).
- Chieffo A et al. 5-Year Outcomes Following Percutaneous Coronary Intervention With Drug-Eluting Stent Implantation Versus Coronary Artery Bypass Graft for Unprotected Left Main Coronary Artery Lesions: The Milan Experience. JACC Cardiovas Interv 2010 June; 3 (6): 595 – 601. PMID: 20630452
- Nakamura K et al. Significance of ST-Segment Elevation in Lead aVR. Arch Intern Med 2012 Mar; 172 (5): 389. PMID: 22412103
- PV Card on 5 things to consider in an abnormal aVR lead
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