Acute Myopericarditis

Acute pericarditis with myocardial involvement, shown by raised troponin with preserved or only mildly reduced ventricular function and no regional wall motion abnormality of a coronary type. About 15 to 30% of patients with acute pericarditis have troponin elevation.

• It affects young men (under 40) most often, usually after a viral illness (enterovirus, adenovirus, parvovirus B19, influenza, SARS-CoV-2), and can follow mRNA vaccination (rare, mild, young males, within days).
• Mechanism: viral or immune mediated inflammation spreading to the epicardial myocardium. Outcome is usually benign, with full recovery in most patients; recurrence is reported in roughly 10 to 30%, and tamponade, constriction and persistent ventricular dysfunction are uncommon (each less than 5%).

• Sharp pleuritic, positional chest pain relieved by leaning forward, radiating to the trapezius ridge, often after a viral illness, with fever, dyspnoea, palpitations. It can mimic myocardial infarction.
• Signs: pericardial friction rub (best heard with the patient leaning forward), tachycardia, low grade fever; signs of heart failure or hypotension only if myocarditis is significant.
• Differential diagnosis: ST elevation myocardial infarction, aortic dissection, pulmonary embolism, pneumothorax, pneumonia and pleurisy, early repolarisation, Takotsubo syndrome, and myocarditis with significant dysfunction.
• Complications: recurrent pericarditis, tamponade (about 1 to 2%), constriction (less than 1%), arrhythmia, and left ventricular dysfunction (rare).

• ECG: diffuse concave ST elevation with PR depression (and PR elevation with ST depression in aVR), evolving over days; no reciprocal ST depression except in aVR and V1.
• High sensitivity troponin (peaks at 24 to 48 hours), CRP, ESR, white cell count; HIV and tuberculosis tests and antinuclear antibody if atypical or recurrent.
• Echocardiography: usually normal or small effusion; exclude regional wall motion abnormality, reduced ejection fraction, and tamponade.
• Coronary angiography or CT coronary angiography if an acute coronary syndrome cannot be excluded (older patients, risk factors, regional wall motion abnormality).
• Cardiac MRI when the diagnosis is uncertain: myocardial oedema and subepicardial late gadolinium enhancement.
• High risk features needing admission and fuller workup: fever greater than 38 degrees Celsius, subacute onset, large effusion or tamponade, failure to respond to NSAIDs within 1 week, immunosuppression, trauma, oral anticoagulation, and myocardial involvement.

• Admit for 1 to 3 days for monitoring (troponin, ECG, echocardiography) and rule out complications. Restrict physical activity until symptoms have resolved and CRP, troponin, ECG and echocardiography are normal; athletes should avoid competitive sport for 3 to 6 months.
• Anti-inflammatory therapy (first line):
  • Ibuprofen 600 mg orally 8-hourly (maximum 2400 mg/day) or aspirin 750 to 1000 mg 8-hourly for 1 to 2 weeks, continued until symptoms resolve and CRP normalises, then tapered by 200 mg (ibuprofen) or 250 to 500 mg (aspirin) every 1 to 2 weeks.
  • Omeprazole 20 mg daily for gastric protection.
  • Colchicine 0.5 mg twice daily (0.5 mg once daily if weight less than 70 kg) for 3 months; reduce the dose in renal impairment and avoid with strong CYP3A4 or P-glycoprotein inhibitors.
• Second line if NSAIDs and colchicine are contraindicated or fail: prednisolone 0.2 to 0.5 mg/kg/day for 2 to 4 weeks with slow taper (a rapid taper or high dose increases recurrence).
• Recurrent or refractory disease (specialist care): anakinra 100 mg SC daily (or 1 to 2 mg/kg/day), rilonacept 320 mg SC loading then 160 mg weekly, or azathioprine 1 to 2 mg/kg/day; evidence is limited. Pericardiectomy is rarely needed.
• Myocardial involvement with reduced ejection fraction or heart failure: stop NSAIDs at high doses, and give ramipril 1.25 to 2.5 mg daily titrated to 10 mg, bisoprolol 1.25 to 10 mg daily (once stable), spironolactone 12.5 to 50 mg daily, and furosemide 20 to 80 mg for congestion.
• Arrhythmia: monitor on telemetry, correct potassium to 4.5 mmol/L or more and magnesium, and use amiodarone for sustained ventricular arrhythmia; avoid class I antiarrhythmics.
• Special groups:
  • Pregnancy: aspirin or ibuprofen up to 20 weeks, then avoid NSAIDs; low dose prednisolone if needed; colchicine data are limited.
  • Children: ibuprofen 5 to 10 mg/kg per dose every 6 to 8 hours; colchicine in children is specialist guided (evidence is limited).
  • Renal impairment: avoid NSAIDs when eGFR is less than 30; halve the colchicine dose, and avoid it when eGFR is less than 10.
  • Elderly and anticoagulated patients: use the lowest effective NSAID dose with gastric protection; avoid NSAIDs in heart failure.
  • Athletes: return to sport only after 3 to 6 months with normal tests, Holter and exercise test.
• Red flags: haemodynamic instability, new heart failure, sustained arrhythmia, large effusion or tamponade, persisting fever, recurrence on tapering.
• Follow up: review at 1 week, 4 to 6 weeks and 3 months; echocardiography at 1 to 3 months; cardiac MRI and Holter at 3 to 6 months if myocardial involvement was significant.