What are the characteristic EKG (electrocardiogram) findings in pericarditis?

Characteristic EKG Findings in Pericarditis

The classic electrocardiographic (ECG) findings in pericarditis include widespread ST-segment elevation and PR-segment depression, which are present in approximately 60% of cases. 1, 2

Key ECG Findings in Pericarditis

• Stage 1 (Early Acute Phase):

  • Diffuse, widespread ST-segment elevation in multiple leads (most characteristic finding)
  • PR-segment depression (except in aVR where PR elevation may be seen)
  • ST-segment depression in lead aVR
  • These changes reflect epicardial inflammation rather than pericardial inflammation, as the parietal pericardium itself is electrically inert 1

• Stage 2 (Days Later):

  • Normalization of ST segments
  • T wave flattening

• Stage 3 (1-2 Weeks):

  • T wave inversions in leads that previously had ST elevation

• Stage 4 (Weeks to Months):

  • Normalization of all ECG changes
  • Return to baseline ECG

Frequency and Clinical Significance

• Typical ECG changes are reported in up to 60% of cases of acute pericarditis 1, 3
• The temporal evolution of ECG changes is highly variable between patients and can be affected by therapy 1
• ECG may be normal at presentation or for days after the initial episode of chest pain 3
• Serial ECGs may reveal specific patterns of temporally dynamic ST elevation, particularly during new episodes of chest pain 3

Differential Diagnosis from Other Conditions

Acute Coronary Syndrome (ACS)

• Pericarditis: Diffuse ST elevation without reciprocal ST depression (except in aVR)
• ACS: Localized ST elevation with reciprocal ST depression in anatomically opposite leads 2, 4

Early Repolarization

• Can mimic pericarditis with ST elevation, ST depression in aVR, and even PR depression 5
• Distinguishing features of early repolarization include:
  • Terminal QRS notching or slurring
  • Absence of clinical symptoms of pericarditis
  • Stable ECG findings over time (vs. dynamic changes in pericarditis) 5

Diagnostic Pitfalls and Caveats

• Not all pericarditis presents with typical ECG changes:

  • Some patients may have normal ECGs despite clinical pericarditis 6
  • ECG changes may be influenced by disease severity, timing of presentation, degree of myocardial involvement, and treatment 3

• ECG changes may indicate myocardial involvement:

  • The pericardium itself is electrically inert; ECG changes imply epicardial/myocardial inflammation 1, 7
  • In a study of pericarditis patients, ECG changes were associated with troponin elevation, suggesting concurrent myocarditis 7

• Atypical presentations require comprehensive evaluation:

  • When clinical suspicion for pericarditis is high but ECG is atypical, additional diagnostic modalities like echocardiography, cardiac CT, or cardiac MRI should be employed 2, 6

Diagnostic Approach

1. ECG is recommended in all patients with suspected pericarditis (Class I recommendation) 1, 2
2. Evaluate for at least 2 of 4 diagnostic criteria (pericarditic chest pain, pericardial rubs, new widespread ST-elevation or PR depression on ECG, pericardial effusion) 1, 2
3. Consider serial ECGs to capture dynamic changes, especially during symptomatic episodes 3
4. Use additional imaging (echocardiography, CT, MRI) when ECG findings are inconclusive 2

Remember that while characteristic ECG changes are helpful in diagnosis, they are present in only about 60% of cases, and their absence does not rule out pericarditis when other clinical features are present.