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Myocarditis

Background Knowledge 🧠

Definition

  • The inflammation of the heart muscle (myocardium).

Epidemiology

  • There is uncertainty regarding true prevalence, but some global estimates report 1.8 million new cases annually.
  • Incidence rates increase by age.

Pathophysiology

  • Damage to the myocardium (e.g. from viruses, toxins, bacteria) β†’ Immune mediated response and inflammatory responseΒ (e.g. cytokine release, T cell activation) Β β†’ Chronic inflammation and fibrosis OR Β resolution of inflammatory response.

Aetiology

  • Most commonly caused by viral infections such as Coxsackievirus, Adenovirus, and Parvovirus B19.

  • Other causes include bacterial infections, fungal infections, parasitic infections, drugs, toxins, and systemic diseases like SLE and sarcoidosis.

Clinical Features πŸŒ‘️

Symptoms

  • Symptoms can range from mild (fatigue, chest pain, dyspnoea)Β to severe (cardiogenic shock, sudden death).

  • Other symptoms include arrhythmias, heart failure, and pericarditis symptoms.

Signs

  • Tachycardia
  • Murmurs
  • S3 heart sound
  • Signs of heart failure

Investigations πŸ§ͺ

Initial Tests

  • Electrocardiogram (ECG): Non-specific ST and T wave changes, arrhythmias.
  • Blood tests: Elevated cardiac enzymes (Troponin), inflammatory markers, and viral titres.

Diagnostic Tests

  • Echocardiogram: Can show reduced ejection fraction, ventricular dilatation, and other structural abnormalities.
  • Cardiac MRI: Considered the gold standard for diagnosis; shows inflammation and oedema.
  • Endomyocardial biopsy: Histological confirmation but used selectively due to invasiveness.

Management πŸ₯Ό

Management

  • Supportive care: Rest, oxygen, and treatment of heart failure symptoms.
  • Immunosuppressive therapy: In certain cases, especially if related to systemic disease.
  • Management of arrhythmias and heart block as needed.
  • Consideration of antiviral therapy based on the specific causative agent.

Prognosis

  • Variable, depending on the cause and severity.
  • Some may have complete recovery while others progress to chronic heart failure.

Complications

  • Cardiac arrhythmias
  • Dilated cardiomyopathy
  • Heart failure
  • Thromboembolism
  • Sudden cardiac death

Key Points

  • Inflammatory disease of the myocardium most commonly caused by a viral infection (e.g Coxsackievirus, Adenovirus).
  • Cardiac MRI is the gold standard tool for diagnosis.
  • Management depends on the underlying cause e.g. antiviral therapy if caused by a viral agent or immunosuppressive therapy if caused by systemic disease such as sarcoidosis.
  • Complications include: arrhythmias, heart failure and dilated cardiomyopathy.

References

Brociek, E., Agata TymiΕ„ska, Andrea Silvio Giordani, Alida L.P. Caforio, Romuald Wojnicz, Grabowski, M. and Krzysztof OzieraΕ„ski (2023). Myocarditis: Etiology, Pathogenesis, and Their Implications in Clinical Practice.Β Biology, 12(6), pp.874–874. doi:https://doi.org/10.3390/biology12060874.

Golpour, A., Patriki, D., Hanson, P.J., McManus, B. and Heidecker, B. (2021). Epidemiological Impact of Myocarditis.Β Journal of Clinical Medicine, [online] 10(4), p.603. doi:https://doi.org/10.3390/jcm10040603.

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