What is pericarditis?

What is Pericarditis?

Pericarditis is inflammation of the pericardium—the double-walled sac surrounding the heart—that most commonly presents with sharp, pleuritic chest pain that improves when sitting forward and worsens when lying supine. 1

Anatomical Context

The pericardium consists of two layers: 1

• Visceral layer (epicardium): The inner serous layer that contacts the myocardium
• Parietal layer: The outer fibrous layer
• Pericardial cavity: The space between these layers, normally containing 15-50 mL of lubricating fluid 1, 2

The pericardium serves three key functions: fixing the heart to the mediastinum, providing protection against infection, and lubricating cardiac motion. 1

Clinical Presentation Spectrum

Pericarditis manifests as one of several distinct syndromes encountered in clinical practice: 1

Temporal Classification

• Acute pericarditis: New-onset episode meeting diagnostic criteria
• Incessant pericarditis: Persistent symptoms without clear remission
• Recurrent pericarditis: Return of symptoms after a documented symptom-free interval of 4-6 weeks
• Chronic pericarditis: Symptoms lasting more than 3 months 3

Associated Conditions

Pericarditis may occur as: 1

• An isolated disease entity
• Part of a systemic disease process (autoimmune disorders, malignancy, uremia)
• With complications including pericardial effusion, cardiac tamponade (<3%), or constrictive pericarditis (<0.5%) 4

Diagnostic Criteria

At least 2 of the following 4 criteria must be present to diagnose acute pericarditis: 3, 4

1. Characteristic chest pain (~90% of cases): Sharp, pleuritic pain that worsens with inspiration and lying supine, improves when sitting forward, and may radiate to the trapezius ridge, neck, back, or left shoulder 3, 5

2. Pericardial friction rub (<30-33% of cases): A highly specific but transient scratchy sound, best heard at the left lower sternal border with the patient sitting upright and leaning forward during brief breath-holding 5, 4

3. ECG changes (25-60% of cases): Widespread concave ST-segment elevation and PR-segment depression, affecting multiple leads rather than a single coronary territory 3, 6, 4

4. New or worsening pericardial effusion (~60% of cases): Detected by echocardiography, though absence does not exclude the diagnosis 3, 4

Pathophysiology and Etiology

Geographic Variation in Causes

In North America and Western Europe: 4, 7

• Idiopathic or presumed viral causes account for 80-90% of cases
• Post-cardiac procedure/surgery pericarditis is the second most common cause
• Tuberculosis represents <5% of cases

In endemic areas: 4

• Tuberculosis is the leading cause and requires antitubercular therapy

Other Important Causes

• Bacterial and other infections 8
• Autoimmune and systemic inflammatory diseases (lupus, rheumatoid arthritis, sarcoidosis) 1, 9
• Post-cardiac injury syndromes (post-MI, post-pericardiotomy, post-trauma) 1
• Uremia and dialysis-related pericarditis 1, 5
• Malignancy and radiation-induced disease 1
• Drug-induced (hydralazine, procainamide) 8

The immune-mediated pathogenesis is supported by the latent period before symptom onset and the response to anti-inflammatory therapy. 1

Myopericarditis: A Critical Distinction

When cardiac troponin is elevated (occurs in up to 50% of acute pericarditis cases) without new focal or diffuse left ventricular dysfunction on imaging, the term "myopericarditis" applies. 1, 5, 4

This indicates predominantly pericardial inflammation with minor myocardial involvement and requires differentiation from acute coronary syndrome, particularly when atypical features like left arm pain are present. 5, 6

Common Diagnostic Pitfalls

• Normal echocardiogram does not exclude pericarditis: Effusion is present in only ~60% of cases 5
• Friction rub is transient: It may disappear and reappear, requiring repeated examinations 5
• Troponin elevation is common: Present in up to 50% of cases and indicates myocardial involvement, not necessarily acute coronary syndrome 5, 4
• Relief with nitroglycerin is not diagnostic: This response neither confirms nor excludes pericarditis or ischemia 5
• Uremic pericarditis may be asymptomatic: Patients may lack typical ECG changes and may not develop tachycardia even during tamponade due to autonomic dysfunction 5

Prognosis

With appropriate treatment, 70-85% of patients have a benign course. 4

• Severe complications (tamponade, constriction) are uncommon in idiopathic pericarditis 1
• Recurrence occurs in 15-30% without colchicine prophylaxis 4, 7
• Constrictive pericarditis develops in <1% of idiopathic cases 1, 4
• Quality of life can be significantly impaired in patients with recurrent disease 1