What is the diagnosis and initial management for chest pain that worsens when lying flat and improves when sitting or leaning forward?

Acute Pericarditis: Diagnosis and Initial Management

Chest pain that worsens when lying flat and improves when sitting or leaning forward is pathognomonic for acute pericarditis, and this positional characteristic effectively excludes pulmonary embolism as the cause. 1

Diagnostic Criteria

Acute pericarditis requires at least 2 of the following 4 criteria for diagnosis: 2, 3

• Sharp, pleuritic chest pain that worsens supine and improves sitting forward (present in ~90% of cases) 2, 3
• Pericardial friction rub on auscultation (highly specific but only audible in <30-35% of patients) 2, 3
• New or worsening pericardial effusion on imaging (detectable in only ~60% of cases) 2, 3
• Characteristic ECG changes: diffuse concave ST-segment elevation with PR-segment depression (present in 25-50% of cases) 2, 3

Immediate Evaluation (First 10 Minutes)

Obtain a 12-lead ECG within 10 minutes to identify the classic pattern of widespread concave ST elevation with PR depression, which distinguishes pericarditis from acute coronary syndrome. 1, 4

Measure cardiac troponin immediately because elevation occurs in up to 50% of acute pericarditis cases, defining myopericarditis rather than isolated pericarditis—though this does not worsen prognosis when left ventricular function is preserved. 4, 5, 2

Order a chest radiograph to evaluate for cardiomegaly (suggesting large effusion), pneumonia, pneumothorax, or mediastinal widening that would indicate alternative diagnoses. 1, 4

Physical Examination Pearls

Listen for the pericardial friction rub with the patient sitting upright, leaning forward, and briefly holding their breath—this position brings the heart closer to the chest wall and is best heard at the left lower sternal border. 4

• The rub may be mono-, bi-, or triphasic, with triphasic being most characteristic 4
• The rub is transient and can disappear and reappear, requiring multiple auscultatory examinations throughout the encounter 4
• Absence of a friction rub does not exclude pericarditis, as it is only audible in approximately one-third of confirmed cases 4, 3

Essential Imaging

Perform transthoracic echocardiography urgently in all patients with suspected pericarditis to detect pericardial effusion, assess for cardiac tamponade, evaluate ventricular wall motion abnormalities, and measure left ventricular systolic function. 4, 5, 3

A normal echocardiogram does not exclude pericarditis, since pericardial effusion is detectable in only 60% of cases. 5

Advanced Imaging When Indicated

Cardiac MRI with gadolinium contrast is the gold standard when diagnostic uncertainty exists or to distinguish myopericarditis from myocardial infarction with nonobstructive coronary arteries, with 94-100% sensitivity for detecting pericardial inflammation. 4, 5

Consider coronary angiography when left arm pain is prominent or when features suggest myocardial involvement, to definitively exclude acute coronary syndrome. 4

First-Line Pharmacologic Management

High-dose aspirin (500 mg to 1 g every 6-8 hours) is the recommended first-line anti-inflammatory therapy to reduce pain and inflammation in acute pericarditis. 1

Colchicine (0.5-0.6 mg once or twice daily for approximately 3 months) should be added to all patients to reduce symptoms and lower recurrence risk from 37.5% to 16.7% (absolute risk reduction of 20.8%). 2, 6, 3

• For patients weighing less than 70 kg, use a reduced daily colchicine dose 1
• With first recurrence, continue colchicine for at least 6 months 2

Acetaminophen may be used for early symptomatic relief of pericardial pain. 1

Critical Medications to Avoid

Glucocorticoids and non-aspirin NSAIDs should be avoided or used with extreme caution because they may increase the risk of recurrent myocardial infarction, impair myocardial healing, and are associated with higher recurrence rates. 1, 3

• Reserve glucocorticoids only for patients with contraindications to first-line therapy, pregnancy beyond 20 weeks' gestation, or systemic inflammatory conditions 3
• For multiple recurrent pericarditis refractory to standard therapy, interleukin-1 blockers may be preferred over corticosteroids 2

Disposition and Risk Stratification

Admit patients to the hospital if any of the following high-risk features are present: 4, 3

• Elevated troponin with ventricular wall motion abnormalities
• Moderate to large pericardial effusion or any signs of tamponade
• Hemodynamic instability or hypotension
• Persistent fever >38°C (>100.4°F)
• Subacute course or failure to respond to NSAIDs within 7 days
• Ventricular arrhythmias

Patients without high-risk features can be managed outpatient with close follow-up to monitor treatment response and C-reactive protein normalization, typically over several weeks. 2, 6

Common Diagnostic Pitfalls

Do not use nitroglycerin response as a diagnostic criterion—relief with nitroglycerin does not confirm or exclude pericarditis or myocardial ischemia. 7, 1

Sharp, pleuritic pain does not completely exclude cardiac ischemia, as approximately 13% of acute coronary syndrome patients present with pleuritic-type chest pain. 1

Do not assume reproducible chest wall tenderness excludes serious pathology, since 7% of patients with palpable chest wall tenderness still have acute coronary syndrome. 1

Recognize that 70-85% of patients with appropriate treatment have a benign course, though 15-30% develop recurrence and a small percentage (<3%) may develop life-threatening complications like cardiac tamponade. 2, 6