What are the typical ECG (electrocardiogram) findings in patients with pericarditis?

Typical ECG Findings in Pericarditis

The most characteristic ECG findings in pericarditis include widespread ST-segment elevation in multiple leads, PR-segment depression (except in aVR where PR elevation may be seen), and ST-segment depression in lead aVR, occurring in approximately 60% of cases. 1

Classic ECG Changes and Their Evolution

The ECG changes in pericarditis typically follow a temporal pattern that can be divided into four stages:

Stage 1 (Early Acute Phase)

• Diffuse, concave ST-segment elevation in multiple leads (typically I, II, aVL, aVF, and V3-V6)
• PR-segment depression (opposite to P wave polarity)
• ST-segment depression in lead aVR (almost always present)
• ST-segment may also be depressed in V1 and occasionally in V2 2

Stage 2 (Days Later)

• ST junctions return to baseline
• PR segments remain deviated
• T waves begin to flatten 2

Stage 3 (1-2 Weeks)

• Generalized T wave inversions develop 2

Stage 4 (Weeks to Months)

• ECG normalizes and returns to pre-pericarditis state 2

Important Diagnostic Considerations

• ECG changes reflect epicardial inflammation rather than pericardial inflammation, as the parietal pericardium itself is electrically inert 2
• Typical ECG changes are present in only up to 60% of cases 2, 1
• The temporal evolution of ECG changes varies significantly between patients and can be affected by therapy 2
• ECG may be normal at presentation or for days after the initial episode of chest pain 3

Differential Diagnosis

Key ECG features to differentiate pericarditis from other conditions:

Acute Coronary Syndrome (ACS)

• Pericarditis: Diffuse ST elevation without reciprocal ST depression
• ACS: Localized ST elevation with reciprocal ST depression 1

Early Repolarization

• Can mimic pericarditis with ST elevation in leads I and II, ST depression in aVR, and sometimes PR depression
• Typically has terminal QRS notching or slurring not seen in pericarditis
• Absence of clinical symptoms of pericarditis 4

Pitfalls and Caveats

• QRS widening and QT interval shortening in leads with ST-segment elevation may help differentiate acute STEMI from pericarditis 5, 6
• ECG changes may indicate concurrent myocarditis rather than simple pericarditis, especially when associated with troponin elevation 7
• ECG changes alone are insufficient for diagnosis; clinical correlation is essential
• Serial ECGs are valuable as they may reveal specific patterns of temporally dynamic ST elevation, particularly during new episodes of chest pain 3

Diagnostic Approach

The European Society of Cardiology recommends:

1. ECG evaluation in all patients with suspected pericarditis (Class I recommendation) 2, 1
2. Diagnosis requires at least 2 of 4 criteria:
   • Pericarditic chest pain
   • Pericardial friction rub
   • New widespread ST elevation or PR depression on ECG
   • Pericardial effusion 1
3. Additional recommended tests:
   • Transthoracic echocardiography
   • Inflammatory markers (CRP, ESR, WBC)
   • Cardiac injury markers (troponin, CK) to identify possible myopericardial involvement 2, 1

Remember that ECG changes may be absent in up to 40% of patients with pericarditis, and their presence strongly suggests epicardial/myocardial involvement rather than isolated pericardial inflammation.