Acute pericarditis

Definition

Acute pericarditis is rapidly developing inflammation of the pericardial sac, frequently with a pericardial effusion. If the inflammation extends to the adjacent myocardium, the condition is called myopericarditis.

Classification

Clinical course

• Acute: symptoms up to 4 weeks.
• Subacute: symptoms over 4 weeks to 3 months.
• Chronic: duration over 3 months.
• Incessant: symptoms persist for longer than 4–6 weeks without a symptom-free interval.
• Recurrent: new episode after a symptom-free interval of 4–6 weeks.

ECG stages

• Stage I — ST pattern: diffuse concave ST elevation + PR depression.
• Stage II: ST normalization + T flattening.
• Stage III: T inversion.
• Stage IV: normalization.

Aetiopathogenesis

• Infectious: in North America and Western Europe mostly viral or idiopathic (presumably viral), e.g. coxsackie B, echo and influenza viruses, SARS-CoV-2, HIV; in endemic regions tuberculosis is the most common cause; purulent bacterial pericarditis is uncommon, e.g. after endocarditis, pneumonia, septicemia or penetrating trauma.
• After myocardial infarction: early post-infarction pericarditis (1–2 % of infarct patients in one cohort) and the now very rare post-myocardial infarction syndrome (Dressler syndrome).
• Post-cardiac injury: post-pericardiotomy syndrome after 5–30 % of pericardiotomies; traumatic and iatrogenic pericarditis, e.g. after catheter procedures or pacemaker placement.
• Systemic diseases: rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, inflammatory bowel disease, sarcoidosis, amyloidosis, rheumatic fever.
• Others: tumors (e.g. breast and lung cancer, leukemia), uremia, hypothyroidism, radiogenic, certain drugs, congenital pericardial anomalies.

Clinical features

• Key findings: pleuritic chest pain, fever and a pericardial friction rub, possibly dyspnea.
• Pain: dull or sharp, precordial or retrosternal, radiating to the neck and trapezius ridge (especially the left); aggravated by thoracic movement, coughing, breathing or swallowing, relieved by sitting up and leaning forward.
• Friction rub: triphasic or systolic-diastolic, often only intermittently audible.
• Accompanying features: tachypnea, non-productive cough, fever, chills, weakness.
• Course: recurrences occur in 15–30 % of idiopathic cases; rarely tamponade is the first manifestation.

Diagnosis

Diagnostic criteria

Classically the diagnosis requires at least 2 of 4 features: typical chest pain, pericardial friction rub, ECG changes, pericardial effusion. Newer criteria start from a typical clinical presentation and count additional findings:

• pericardial friction rub
• diffuse PR depression and/or ST elevation on the ECG
• raised CRP or raised ESR
• new or worsening pericardial effusion on imaging
• pericardial edema or late gadolinium enhancement on cardiac MRI

Definite with a typical presentation and at least 2 additional findings, possible with 1 additional finding, unlikely with no additional finding.

Investigations

• ECG: changes of ST segment, PR segment and T wave in most leads; unlike infarction no reciprocal ST depression (except in aVR and V1) and no pathological Q waves.
• Echocardiography: usually an effusion (often normal in purely fibrinous pericarditis); new wall motion abnormalities or abnormal strain suggest myocardial involvement.
• Cardiac MRI: detection and extent of pericardial inflammation; extension to the myocardium in up to 15–24 % of cases.
• Laboratory: leukocytosis, CRP and ESR; troponin is often raised due to epicardial inflammation, very high levels suggest myopericarditis.
• Search for the cause: chest X-ray or CT, blood count, autoimmune tests, HIV testing where appropriate; if tuberculosis is suspected, an interferon-gamma release assay, although only culture of pericardial fluid confirms or excludes the diagnosis; cytology and culture of the fluid or pericardial biopsy when the cause is unclear.

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Further reading (open access)

1. MSD Manual Professional: Pericarditis
2. StatPearls: Pericarditis

Cross-references