What is pericarditis?

What is Pericarditis

Pericarditis is inflammation of the pericardium (the sac surrounding the heart) that presents with characteristic chest pain and is diagnosed when at least 2 of 4 specific clinical criteria are met. 1

Definition and Diagnostic Criteria

Acute pericarditis is diagnosed when at least 2 of the following 4 criteria are present: 1, 2, 3

• Sharp, pleuritic chest pain that is typically retrosternal, worsens with lying supine, improves when sitting up and leaning forward, and may radiate to the trapezius ridge, neck, back, or left shoulder (present in ~90% of cases) 1, 4, 2
• Pericardial friction rub on auscultation—highly specific but transient, heard in only 18-33% of patients 1, 3
• New or worsening pericardial effusion on echocardiography (present in ~60% of cases) 1, 3
• Characteristic ECG changes: diffuse concave ST-segment elevation and/or PR-segment depression (present in 25-50% of cases) 4, 2, 3

Clinical Presentation

The chest pain of pericarditis has distinctive features that help differentiate it from other causes: 1, 4

• Positional nature: Pain changes with inspiration and body position, characteristically improving when sitting upright and leaning forward 1, 4
• Pleuritic quality: Sharp pain that worsens with deep breathing 2, 3
• Radiation pattern: May radiate to the neck, back, or left shoulder, though left arm radiation is not classical and should raise suspicion for myocardial involvement (myopericarditis) 4

Etiology

The causes vary significantly by geographic location: 2, 5

• In North America and Western Europe: 80-90% of cases are idiopathic or presumed viral 2, 5
• In endemic areas: Tuberculosis is the most common cause and requires specific antitubercular therapy 2, 5
• Other causes: Post-cardiac injury syndromes (after MI, cardiac surgery, or procedures), autoimmune diseases (lupus, rheumatoid arthritis, scleroderma), radiation, malignancy, and uremia 6, 1

Important Clinical Variants

Myopericarditis occurs when pericarditis is accompanied by myocardial involvement, indicated by elevated cardiac troponins (present in up to 50% of acute pericarditis cases) without new focal or diffuse left ventricular dysfunction on imaging. 6, 1, 4 This variant may present with features mimicking acute coronary syndrome, including left arm pain, requiring careful differentiation. 4

Temporal Classification

Pericarditis is classified based on duration: 1

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

Prognosis and Complications

The overall prognosis is favorable in most cases: 6, 2

• 70-85% of patients have a benign course with appropriate treatment 2
• Recurrence occurs in 15-30% without colchicine prophylaxis, but drops to approximately 16.7% with colchicine 2, 5
• Serious complications are uncommon: cardiac tamponade occurs in <3% and constrictive pericarditis in <0.5-1% of cases 6, 1, 2

Common Pitfalls

Several diagnostic pitfalls warrant attention: 4, 3

• Absence of pericardial effusion does not exclude pericarditis—effusion is present in only 60% of cases 1, 4
• Pericardial friction rubs are transient and may disappear and reappear, requiring multiple examinations 4, 3
• Elevated troponin does not necessarily indicate MI—it may simply indicate myopericarditis, which generally has a benign prognosis when left ventricular function is preserved 6, 1
• Left arm pain in suspected pericarditis should raise concern for myocardial involvement and may require coronary angiography or cardiac MRI to exclude acute coronary syndrome 4