Activate or Wait – 004
86 year-old woman with two hours of dull chest pain and dizziness. Ex-smoker with hypertension and dyslipidaemia.
ETA 20 minutes.
ECG interpretation
Inferolateral STEMI complicated by junctional bradycardia
- ST elevation inferolaterally in leads II, III, aVF and V4-V6
- Reciprocal ST depression in aVR, aVL and V2
- Hyperacute T-waves seen inferiorly
- Junctional bradycardia with a heart rate of 42 beat per minute
The presence of widespread inferolateral ST elevation indicates a large territory right coronary artery (RCA) infarct affecting the inferior and lateral walls.
Junctional bradycardia is likely due to a combination of:
- Sinus node dysfunction due to impaired blood flow via the sinoatrial nodal artery, which arises from the proximal RCA in 60% of people
- Vagal effects of an inferior STEMI (the bezold-jarisch reflex)
The extent of the ST changes and the presence of junctional bradycardia hints at a more proximal RCA occlusion and a higher risk case.
Note that the terms junctional bradycardia and junctional escape rhythm are synonymous, simply referring to an escape rhythm arising at the AV node. Because the rate of spontaneous depolarisation at the level of the AV node is usually 40-60 bpm, this is often a bradyarrhythmia.
Outcome
Key Finding:
Proximal right coronary artery (RCA) occlusion with thrombus.
Findings:
- Left Main Coronary Artery — normal
- Left Anterior Descending Coronary Artery — mild coronary artery disease
- Left Circumflex Coronary Artery — normal
- Right Coronary Artery — proximal occlusion with thrombus
Plan:
Proximal RCA occlusion with thrombus
Proceed to percutaneous coronary intervention of proximal RCA.
- Dual antiplatelet therapy for 12 months. Lifelong aspirin
- Aggressive cardiovascular risk factor management
- Admit to CCU
Clinical Pearls
- Bradyarrhythmias are common in inferior MI due to impaired blood flow via the sinoatrial nodal artery and/or AV nodal artery
- The presence of sinus node dysfunction (sinus bradycardia, sinuses pauses, junctional bradycardia) indicates a more proximal RCA or left circumflex occlusion and a higher risk patient
References
Further reading
- Buttner R, Burns E. Inferior STEMI. LITFL
- Nickson C. STEMI Management. LITFL
Online resources
- Wiesbauer F, Kühn P. ECG Mastery: Yellow Belt online course. Understand ECG basics. Medmastery
- Wiesbauer F, Kühn P. ECG Mastery: Blue Belt online course: Become an ECG expert. Medmastery
- Kühn P, Houghton A. ECG Mastery: Black Belt Workshop. Advanced ECG interpretation. Medmastery
- Rawshani A. Clinical ECG Interpretation ECG Waves
- Smith SW. Dr Smith’s ECG blog.
ACTIVATE or WAIT
EKG Interpretation
Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Co-creator of the LITFL ECG Library. Twitter: @rob_buttner
Dr. Stephen W. Smith is a faculty physician in the Emergency Medicine Residency at Hennepin County Medical Center (HCMC) in Minneapolis, MN, and Professor of Emergency Medicine at the University of Minnesota. Author of Dr Smith's ECG Blog | Bibliography | X |
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Does anyone have any explanation as to how the lateral leads get ST elevation when the RCA is occluded? Does the RCA somehow provide perfusion to the lateral wall as well? Thanks.