What are the ECG changes in viral pericarditis?

ECG Changes in Viral Pericarditis

The ECG changes in viral pericarditis follow a characteristic four-stage evolution with widespread ST-segment elevation and PR-segment depression being the hallmark findings, though these classic changes are only present in approximately 60% of cases. 1

Typical ECG Evolution in Viral Pericarditis

Stage I (Early Acute Phase)

• Widespread concave upward ST-segment elevation in anterior and inferior leads (I, II, aVL, aVF, V3-V6) 1
• PR-segment depression (opposite to P wave polarity) 1
• ST-segment depression in aVR, frequently in V1, and occasionally in V2 1
• Typical lead involvement: I, II, aVL, aVF, and V3-V6 1

Stage II (Early Evolution)

• Early Stage II: ST junctions return to baseline, but PR-segment remains deviated 1
• Late Stage II: T waves progressively flatten and begin to invert 1

Stage III (Later Evolution)

• Generalized T wave inversions 1
• At this stage, pericarditis cannot be differentiated by ECG from diffuse myocardial injury, "biventricular strain," or myocarditis if this is the first ECG recorded 1

Stage IV (Resolution)

• ECG returns to pre-pericarditis state 1
• In some cases, stage IV does not occur, resulting in permanent T wave inversions and flattenings 1

Important Diagnostic Considerations

Differentiating Features from Acute Coronary Syndrome

• Pericarditis shows widespread ST elevation without reciprocal changes 2
• In lead V6, pericarditis is likely if the J point is >25% of the height of the T wave apex (using the PR segment as a baseline) 1
• Unlike early repolarization, ECG changes in pericarditis acutely evolve through the stages described above 1

Atypical ECG Presentations

• Up to 43% of patients may have atypical ECGs 3
• Some patients may have no ST deviations at all, or only in limited leads 3
• PR segment shifts may be the only ECG sign in some cases 3
• ECG may be normal at presentation or for days after the initial episode of chest pain 4

Myocardial Involvement

• When pericarditis is accompanied by myocarditis (myopericarditis), cardiac biomarkers may be elevated 1
• Troponin I is detectable in approximately 49% of acute pericarditis patients, particularly those with ST elevation 1
• Presence of elevated cardiac biomarkers should prompt evaluation for myocardial involvement 1

Clinical Pearls and Pitfalls

Diagnostic Challenges

• ECG changes may be absent in up to 7-15% of cases 4, 3
• Serial ECGs are essential as changes can evolve rapidly and may only be evident during episodes of chest pain 4
• ECG changes are affected by disease severity, timing of presentation, degree of myocardial involvement, and treatment 4

Management Implications

• ECG is recommended in all patients with suspected acute pericarditis (Class I recommendation) 1
• Hospitalization should be considered for patients with high-risk features including elevated cardiac biomarkers suggesting myopericarditis 2
• Exercise restriction is recommended until symptom resolution and normalization of inflammatory markers 2

Follow-up

• Evaluation of response to anti-inflammatory therapy is recommended after 1 week 1
• Serial ECGs should be performed to monitor disease evolution and response to treatment 1, 4

By recognizing these characteristic ECG patterns and their evolution, clinicians can more accurately diagnose viral pericarditis and differentiate it from other conditions with similar presentations, particularly acute coronary syndromes.