STEMI mimickers

Question 1

What are some of the most common STEMI mimickers?

Answer 1

• LBBB
• RBBB
• Paced rhythms
• Ventricular escape rhythm
• Pericarditis
• Dissecting aortic aneurysm
• Left ventricular hypertrophy
• Benign early repolarization
• Ventricular aneurysm

Question 2

Explain the physiology behind ECG changes in LBBB

Answer 2

• Electrical conduction is blocked through the left bundle branch
• Impulse spreads to the right ventricle via the RBBB and then to the left ventricle via the septum
• Produces tall “R” waves in lateral leads (V5, V6) and deep “S” waves in the right precordial leads (VI-V3)
• Ventricles are activated right to left, rather than simultaneously, which produces “M” shape in lateral leads and “W” in precordial leads (VI)

Question 3

Explain the physiology behind ECG changes in RBBB

Answer 3

• Activation of right ventricle is delayed but left ventricle is activated normally
• Early portion of QRS complex is unchanged
• Delayed activation to right ventricle produces a secondary “R” wave in Leads VI-V3, slurred ‘s” waves in lateral leads, and an “M” shaped QRS in VI-V3
• ST segment depression and T wave inversion normal in VI-V3

Question 4

What are the causes of LBBB?

Answer 4

• Acute MI
• Aortic stenosis
• Coronary Artery Disease
• HTN
• Digoxin toxicity
• Hyperkalaemia
• Disease of the conduction system

Question 5

What are the causes of RBBB?

Answer 5

• Right ventricular hypertrophy/cor pulmonale
• Pulmonary embolis
• Ischemic heart disease
• Myocarditis or cardiomyopathy
• Congenital heart disease
• Disease of the conduction system

Question 6

Notching or slurring J point is an indication of which mimicker?

Answer 6

BER

Question 7

T waves with a smaller amplitude than the hyperactive T waves seen in STEMIs are indicative of which mimicker?

Answer 7

Ventricular aneurysm