Diagnosis and Initial Evaluation of Acute Pericarditis
Diagnostic Criteria
Acute pericarditis is diagnosed when at least two of the four cardinal features are present: (1) sharp, pleuritic chest pain that worsens in the supine position and improves when sitting forward, (2) a pericardial friction rub, (3) new widespread concave ST‑segment elevation or PR‑segment depression on ECG, and (4) a new or worsening pericardial effusion on echocardiography. Class I recommendation. 1
The classic ECG changes are observed in only 25 %–60 % of patients, making them an unreliable sole criterion. 1
A pericardial effusion is detected in roughly 60 % of acute pericarditis cases. 1
A pericardial friction rub can be heard in up to 85 % of cases but is often transient and may be absent on initial examination. 2
Initial Diagnostic Testing (Mandatory Work‑up)
| Test | Purpose | Recommendation Strength |
|---|---|---|
| 12‑lead ECG | Detects widespread concave ST‑elevation and PR‑depression; may be absent in 40‑75 % of presentations. | Class I |
| Transthoracic echocardiography | Identifies pericardial effusion, assesses size, and excludes tamponade. | Class I |
| Chest X‑ray | Usually normal; may reveal a large effusion when volume exceeds ~300 mL. | Class I |
| Inflammatory markers (CRP, ESR, WBC) | Confirm systemic inflammation and allow monitoring of therapeutic response. | Class I |
| Myocardial injury markers (troponin, CK‑MB) | Detect concurrent myocarditis (myopericarditis). | Class I |
All five investigations are endorsed as *Class I recommendations for every patient with suspected acute pericarditis. 3, 4
Clinical Features and Nuances
The pericardial friction rub is highly specific for pericarditis but frequently absent or fleeting, underscoring the need for careful auscultation (end‑expiration, patient seated and leaning forward). 2
A prodromal syndrome of fever, malaise, and myalgia is common; however, elderly patients may lack fever. 2
ECG findings are highly variable and temporally dynamic, often changing rapidly during the disease course; serial ECGs are therefore essential. 5
The principal differential diagnoses include acute coronary syndrome with ST‑elevation and early repolarization patterns. 1, 5
Supporting Findings (Non‑mandatory but Helpful)
Elevated inflammatory markers (CRP, ESR, WBC) are frequent and serve to monitor disease activity. 1, 5
Advanced imaging (cardiac CT or cardiac magnetic resonance) can visualize pericardial inflammation in atypical or equivocal cases. 1
Troponin elevation favors a diagnosis of myopericarditis rather than isolated pericarditis. 5, 2
Special Considerations
In young adults (e.g., a 26‑year‑old with sinus arrhythmia), the presence of sinus arrhythmia does not contribute diagnostically; the focus remains on the four cardinal criteria. 1
Do not wait for all four criteria to be present; the diagnosis is confirmed once any two are met, acknowledging that classic ECG patterns appear in < 60 % and friction rubs are often absent. 1, 3, 4
Myopericarditis: Diagnosis and Associated Factors
Myocardial Involvement in Acute Pericarditis
- Troponin elevation signifies concurrent myocardial involvement (myopericarditis) in patients presenting with acute pericarditis. 6
- The classic presentation of myopericarditis comprises chest pain with pericardial signs together with raised myocardial injury markers such as troponin and CK‑MB. 6
Diagnostic Work‑up for Elevated Troponin
- When troponin is elevated in the setting of acute pericarditis, coronary angiography is recommended to rule out an acute coronary syndrome. 6
Common Preceding Illnesses
- A notable proportion of acute pericarditis episodes are preceded by or occur alongside acute respiratory infections (e.g., tonsillitis, pneumonia) or gastroenteritis. 6