What is the initial workup and treatment for myocarditis and pericarditis?

Initial Workup for Myocarditis and Pericarditis

All patients with suspected myocarditis or pericarditis require immediate ECG, transthoracic echocardiography, chest X-ray, and blood tests including inflammatory markers (CRP, ESR, white blood cell count) and cardiac injury markers (troponin, creatine kinase). 1

First-Level Diagnostic Evaluation (Mandatory for All Cases)

Clinical Assessment

• Auscultation for pericardial friction rub 1
• Look for pericarditic chest pain (sharp, retrosternal, pleuritic, positional relief when leaning forward) 1
• Assess for symptoms suggesting myocarditis: dyspnea, fatigue, palpitations, syncope, or chest pain mimicking acute MI 1

Essential Laboratory Tests

• Inflammatory markers: CRP and/or ESR, white blood cell count with differential 1
• Cardiac injury markers: Troponin I/T and creatine kinase 1
  • Troponin elevation suggests myocardial involvement (myopericarditis) 1
  • Note: Troponin may be elevated in only 34% of myocarditis cases, so normal values don't exclude disease 1
• Renal function, liver tests, thyroid function 1

Electrocardiogram (ECG)

• Pericarditis patterns: Widespread ST-segment elevation, PR-segment depression (seen in up to 60% of cases) 1
  • However, ECG may be normal in up to 75% of pericarditis cases 2
  • Serial ECGs are critical as changes evolve rapidly 3
• Myocarditis patterns: QRS width >120 ms (predicts worse outcomes), low voltage with thickened LV walls (suggests edema), conduction abnormalities, arrhythmias 1, 4

Transthoracic Echocardiography

• Assess for: Pericardial effusion (>20 mm diastolic echo-free space indicates large effusion), cardiac tamponade, wall motion abnormalities, ventricular function, wall thickness 1
• Critical for myocarditis: Evaluate both left AND right ventricular function, as RV dysfunction predicts worse outcomes 5

Chest X-ray

• Identifies: Pericardial effusion >300 ml (increased cardiothoracic ratio), pleuro-pulmonary involvement 1

Risk Stratification: Who Requires Hospital Admission?

Admit immediately if ANY of these high-risk features are present 1:

Major Risk Factors (Require Hospitalization)

• Fever >38°C (>100.4°F) 1
• Subacute course (symptoms developing over days/weeks without clear acute onset) 1
• Large pericardial effusion (diastolic echo-free space >20 mm) 1
• Cardiac tamponade 1
• Failure to respond to NSAIDs within 7 days 1

Additional High-Risk Features for Myocarditis

• Ventricular arrhythmias or heart block (require prolonged ECG monitoring and mandatory admission due to sudden cardiac death risk) 4
• Acute fulminant myocarditis: Refractory ventricular tachyarrhythmias with severe acute heart failure 4
• Hemodynamically compromising sustained ventricular arrhythmias or aborted cardiac arrest 4
• Progressive wall motion abnormalities with deteriorating LV function 4
• Persistent or fluctuating troponin concentrations, widening QRS complex 4

Minor Risk Factors (Consider Hospitalization)

• Myopericarditis (concurrent myocardial involvement) 1
• Immunosuppression 1
• Trauma 1
• Oral anticoagulant therapy 1

Low-risk patients (absence of all above features) can be managed as outpatients with empiric anti-inflammatory therapy and 1-week follow-up 1

Second-Level Testing (When First-Level Insufficient or High-Risk Features Present)

Cardiac Magnetic Resonance (CMR)

• Recommended as second-level imaging for both pericarditis and myocarditis 1
• For myocarditis: Highly sensitive for detecting epicardial or mid-wall delayed gadolinium enhancement, myocardial edema on T2-weighted sequences 1, 4
• Should be performed even before endomyocardial biopsy in suspected myocarditis 4

Cardiac CT

• Indicated for: Assessing pericardial calcifications, pericardial thickness, degree of pericardial involvement 1

Etiology-Specific Testing (High-Risk Patients Only)

The ESC guidelines state it is NOT mandatory to search for etiology in all patients, especially in low TB prevalence countries, due to relatively benign course and low diagnostic yield 1

However, pursue specific etiology testing if high-risk features present 1:

Suspected Autoimmune Disease

• ANA, ENA, ANCA 1
• Ferritin (if Still disease suspected) 1
• ACE and 24-hour urinary calcium (if sarcoidosis suspected) 1
• Consider PET for large vessel arteritis or sarcoidosis 1

Suspected Tuberculosis

• IGRA test (Quantiferon, ELISpot) 1
• Chest CT scan 1

Suspected Neoplasm

• Chest and abdomen CT scan, consider PET 1

Suspected Viral Infection

• PCR for viral genomes (preferred over serology) 1
• Consider serology for HCV and HIV 1

Suspected Bacterial Infection

• Blood cultures before antibiotics 1
• Serology for Coxiella burnetii (Q-fever), Borrelia (Lyme disease) 1

Pericardiocentesis or Surgical Drainage

Indicated for 1:

• Cardiac tamponade 1
• Suspected bacterial or neoplastic pericarditis 1
• Symptomatic moderate to large effusions not responding to medical therapy 1

Pericardial fluid analysis 1:

• Cytology with cell count (centrifugation improves yield) 1
• PCR for tuberculosis 1
• Mycobacterium cultures, aerobic and anaerobic cultures 1
• Protein and LDH (though not validated for pericardial fluid) 1

Endomyocardial Biopsy (Myocarditis)

Perform in these specific scenarios 4:

• Life-threatening disease course: acute fulminant myocarditis with refractory ventricular tachyarrhythmias in severe acute heart failure 4
• Hemodynamically compromising sustained ventricular arrhythmias or aborted cardiac arrest 4
• Suspected giant cell myocarditis or sarcoidosis 4

Initial Treatment

For Pericarditis

• First-line therapy: Aspirin or NSAIDs PLUS colchicine (0.5 mg twice daily or once daily if <70 kg or intolerant) for 3 months 1
• Corticosteroids are NOT recommended as first-line therapy 1
• Use CRP to guide treatment duration and assess response 1
• Reassess at 1 week to evaluate response to anti-inflammatory therapy 1

For Myocarditis

• Treat heart failure and arrhythmias per standard guidelines 1
• Address underlying cause if identified 1
• Specific immunosuppressive therapy only for certain etiologies (e.g., giant cell myocarditis, cardiac sarcoidosis) 1

Critical Pitfalls to Avoid

• Don't rely solely on ECG: Classic ST-elevation or PR-depression occurs in <60% of pericarditis cases 1, 2
• Don't dismiss normal troponin: Only 34% of myocarditis patients have elevated troponin 1
• Don't forget to assess RV function: RV dysfunction in myocarditis predicts worse outcomes than LV dysfunction 5
• Don't pursue extensive etiology workup in low-risk patients: Low diagnostic yield and unnecessary cost 1
• Don't use corticosteroids first-line for pericarditis: Associated with increased recurrence risk 1