ECG Pointers: Pericarditis

Author: Jamie Santistevan, MD (EM Physician, Presbyterian Hospital, Albuquerque, NM). Edited by: Alex Koyfman, MD (@EMHighAK) and Brit Long, MD (@long_brit)

Welcome to this edition of ECG Pointers, an EMDocs series designed to give you high yield tips about ECGs to keep your interpretation skills sharp. For a deeper dive on ECGs, we will include links to other great ECG FOAMed!

The Case: A 25-year old male presents with sudden onset, substernal chest pain radiating behind his left shoulder. He feels short of breath and is diaphoretic.

Sinus rhythm with a rate of about 75. The axis is normal. The QRS is narrow. There is concave ST segment elevation in leads I, II>III and V3-V6 and ST depression in leads aVR and V1. There is slight ST depression and T-wave inversion in V2.

The computer read this ECG as ******ACUTE MI******. The Cath lab is activated. The repeat ECG several minutes later:

Diffuse ST elevation again seen but the T wave in lead V2 is now upright. There is PR depression seen best in lead II and ST depression with PR elevation in aVR.

The EM physician was concerned and patient was taken quickly to the cath lab where left heart catheterization showed clean coronary arteries. An echocardiogram showed no wall motion abnormalities and no pericardial effusion. Initial troponin I returned at 2.593ng/mL. The patient was diagnosed with myoperciarditis.

What is pericarditis?

Pericarditis results from inflammation of the pericardium and can also cause inflammation to the underlying epicardium (myopericarditis).

Patients often complain of sub sternal chest pain that is sharp, pleuritic and worse when leaning forward. It often radiates to the trapezius ridge. A low-grade fever and tachycardia may also be present. If you work in the quietest emergency department ever, you might hear a friction rub secondary to pericardial effusion.

The most common causes of pericarditis are viral (cocksackie virus) but other infectious causes include bacteria, fungus and tuberculosis. Also, don’t forget that uremia, a recent MI, autoimmune diseases and trauma can also cause pericarditis.

The diagnosis of pericarditis requires 2 or more clinical features:

• Classic chest pain history: sharp, pleuritic and positional with radiation to the trapezius ridge
• Pericardial friction rub
• Pericardial effusion on echocardiogram
• Characteristic EKG findings

What to look for on the ECG:

• There will be widespread concave ST elevation. The ST elevation crosses multiple vascular territories: Inferior (II, III and aVF), anterior (V2-V4) and lateral (I, aVL, V5 and V6).
• There may be PR depression paired with the ST elevation (although this may be transient).
• There will be reciprocal ST depression and PR elevation in aVR (and sometimes V1).
• There may be downsloping of the TP segment (Spodick’s sign)

An acute ST elevation MI (STEMI) can be misdiagnosed as pericarditis. When facing an ECG that resembles pericarditis, the first step should always be to think about STEMI. What are some findings that should point you towards STEMI and NOT pericarditis?

• If there is flat or convex ST elevation—think STEMI
• If there is reciprocal ST depression in any lead other than aVR or V1— think STEMI
• If there is ST elevation in III greater than II—think STEMI
• If serial ECGs show dynamic changes or development of Q waves—think STEMI
• What about the clinical history? Unfortunately, it’s not always reliable because some patients with acute MI will have pleuritic or positional chest pain!

Check out this case where acute MI was misdiagnosed as pericarditis on Dr. Smith’s ECG blog: http://hqmeded-ecg.blogspot.com/2016/02/pericarditis-or-stemi-difference-can-be.html

What are the main ECG pointers for pericarditis?

• Pericarditis and STEMI can be very difficult to differentiate on ECG!
• The ST elevation of pericarditis should be concave (smiley-face)
• The ST elevation should be diffuse, not localized to a single vascular territory
• In pericarditis, ST depression should only be found in aVR and V1
• If you’re not sure, get serial ECGs and err on the side of caution!

But wait, here’s some more ECG FOAMed:

For more on ECG findings in pericarditis, see this post on Life in the Fast Lane: https://lifeinthefastlane.com/ecg-library/basics/pericarditis/

What about pericarditis in kids? Check out Sean Fox’s blog post: http://pedemmorsels.com/pericarditis/

There’s a PV card for pericarditis diagnosis and treatment on the Academic Life in EM blog: https://www.aliem.com/2015/02/pv-card-pericarditis-diagnosis-treatment/

And a special thanks to Drs. John Bigelow and Michael Bauman for sharing these ECG’s and interesting case with me!