Left Main Coronary Artery Occlusion: ST Elevation in aVR

Left Main Coronary Artery Occlusion: ST Elevation in aVR Posted By:
...

During my ECG training, we were taught that the findings from lead aVR were only important for supportive evidence of pericarditis. I subsequently learned differently. This post will look at ECG findings associated with left main coronary artery (LMCA) disease and explore the significance of ST-segment elevation in the aVR "forgotten lead."

Early identification of LMCA disease is critical because acute occlusion can cause rapid hemodynamic and electrical deterioration. LMCA insufficiency due to critical stenosis of the left main artery is important to recognize because these patients can progress to complete occlusion and are likely to require surgical intervention, such as CABG.

The mechanism of ST elevation (STE) in aVR is multifactorial. Lead aVR is electrically opposite to the left-sided leads I, II, aVL, and V4-6; therefore, ST depression in these leads will produce reciprocal ST elevation in aVR. Additionally, lead aVR directly records electrical activity from the right upper portion of the heart. This includes the right ventricular outflow tract and the basal portion of the interventricular septum, so infarction in this area could theoretically produce ST elevation in aVR. Diffuse subendocardial ischemia with ST depression in the lateral leads produces reciprocal change in aVR and infarction of the basal septum (ie, a STEMI involving aVR).

ST elevation in aVR is not entirely specific to LMCA occlusion. It may also be seen with:

  • Proximal left anterior descending artery (LAD) occlusion
  • Severe triple-vessel disease (3VD)
  • Diffuse subendocardial ischemiaie, due to O2 supply/demand mismatch, following resuscitation from cardiac arrest

Note: Some of the authors argue that using the term "LMCA occlusion" is inaccurate, as most of these patients have at least some flow in their LMCA (ie, incomplete LMCA occlusion) whereas a complete LMCA occlusion would rapidly lead to STEMI, cardiogenic shock, and death.

Typical ECG findings with LMCA occlusion:

  • Widespread horizontal ST depression, most prominent in leads I, II and V4-6
  • ST elevation in aVR ≥1mm
  • ST elevation in aVR ≥V1

Review this ECG in a patient with acute chest pain:

ECG of acute chest pain

There is diffuse ST depression, with ST elevation in aVR. This is diffuse subendocardial ischemia. The ST elevation in aVR is reciprocal to the ST depression vector that is directed anterior, lateral, and inferior (toward leads II and V5). STE in aVR is thus reciprocal ST elevation!

ST-elevation myocardial infarction involving the left main coronary artery has been associated with significant morbidity and mortality. When reviewing ECGs in patients with chest pain, always be on the lookout for this phenomenon.

References
  • Baek JY, Seo SM, Park HJ, Kim PJ, et al. Clinical outcomes and predictors of unprotected left main stem culprit lesions in patients with acute ST segment elevation myocardial infarction. Catheter Cardiovasc Interv. 2014;83:E243-E250.
  • Smith SW. Updates on the electrocardiogram in acute coronary syndromes. Curr Emerg Hosp Med Rep. 2013;1:43-52.
  • Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography. Hoboken, NJ: Wiley-Blackwell; 2009.
  • Knotts RJ, Wilson JM, Kim E, Huang HD, Birnbaum Y. Diffuse ST depression with ST elevation in aVR: Is this pattern specific for global ischemia due to left main coronary artery disease? J Electrocardiol. 2013;46:240-248

Share

Filed under: Cardiometabolic

Related
Phase III FLOW Trial Results Establishes Semaglutide’s Role in Treating T2D and CKD

Phase III FLOW Trial Results Establishes Semagluti ...

The highly anticipated results of the FLOW (Evaluate Renal Function with Semaglutide Once Weekly) tr ...

Filed under: Cardiometabolic, NPs & PAs


Continue Reading
The Gift of Time and Key Connection Between Diabetes Mellitus and Autoimmune Disorders

The Gift of Time and Key Connection Between Diabet ...

Are you aware that approximately 64,000 Americans are diagnosed with type 1 diabetes (T1D) each year ...

Filed under: Cardiometabolic


Continue Reading
The Importance of Shared Decision-making in Obesity

The Importance of Shared Decision-making in Obesit ...

Many areas of healthcare are starting to talk about the importance of shared decision-making (SDM), ...

Filed under: Cardiometabolic, NPs & PAs


Continue Reading
Addressing ASCVD Risk in HIV: An Update to the DHHS HIV Guidelines

Addressing ASCVD Risk in HIV: An Update to the DHH ...

The incidence of atherosclerotic cardiovascular disease (ASCVD) is estimated to be twice as high in ...

Filed under: Infectious Diseases, Preventive Medicine, Public Health, Cardiometabolic, NPs & PAs


Continue Reading
Understanding the Multifactorial Etiology of Obesity and the Metabolic Adaptations to Weight Loss

Understanding the Multifactorial Etiology of Obesi ...

Obesity Causes Overeating, Not the Other Way AroundOne of my favorite quotes from Dr Lee Kaplan is, ...

Filed under: Cardiometabolic, NPs & PAs


Continue Reading
Atrial Fibrillation: Optimizing Outcomes by Addressing Social Determinants of Health and Implicit Bias

Atrial Fibrillation: Optimizing Outcomes by Addres ...

Atrial fibrillation (AF) is the most common sustained arrhythmia diagnosed, and its prevalence is ex ...

Filed under: Cardiometabolic, NPs & PAs


Continue Reading