Makindo Medical Notes

Related Subjects: |Assessing Breathlessness |Chronic Heart Failure |Acute Heart Failure and Pulmonary Oedema |Loop Diuretics |Chest X Ray Interpretation

📖 About

• ❤️ Acute myocarditis = inflammation of the heart muscle → risk of fatal arrhythmias & acute HF.
• 👶👩‍🦳 Affects any age; triggered by infections (viral 🦠, bacterial 🧫, parasitic 🪱) or non-infectious causes (autoimmune ♻️, toxins ☠️, drugs 💊).
• ⚡ Presentation: acute, subacute, or chronic. Severe cases → cardiogenic shock.
• 🫀 Long-term risk = dilated cardiomyopathy → chronic HF.

🧬 Aetiology & Pathology

• Inflammation → dilated, poorly functioning LV with ↑ troponins 📈.
• Types:
  • Lymphocytic → viral/drugs.
  • Eosinophilic → parasites/hypersensitivity.
  • Giant-cell → fulminant, autoimmune, poor prognosis.
  • Granulomatous → sarcoidosis, arrhythmias.

🦠 Causes

🩺 Clinical Presentation

• Viral prodrome: fever 🤒, myalgia, malaise.
• Chest pain ❤️🔥 (often pericarditic).
• Fatigue, SOB 🫁, palpitations ⚡.
• Syncope → malignant arrhythmias.
• Signs: murmurs (MR), S3/S4, rub, tachyarrhythmias, cardiogenic shock 🫀.

🧪 Investigations

• Bloods: ↑ CRP/ESR, ↑ troponin/BNP 📈, ± autoantibodies.
• ECG: AF, VT, LBBB, ST/T changes ⚡.
• CXR: cardiomegaly, pulmonary edema.
• Echo: LV dysfunction, effusion.
• Cardiac MRI 🖼️: oedema, fibrosis (Lake Louise criteria).
• Biopsy (gold standard 🏆): lymphocytic infiltrates, necrosis.

🚑 Management

• ABC, oxygen, correct electrolytes.
• CCU monitoring 📡 with telemetry.
• Bed rest 🛌, avoid exertion.
• HF therapy: ACEi/ARB, β-blocker, diuretics.
• Anticoagulate if AF or mural thrombus risk.
• Advanced support: IABP, ECMO, transplant for refractory cases.
• Specific therapy: antivirals (rare), immunosuppression for giant-cell/sarcoid, antiparasitic for Chagas.

⚠️ Complications

• Dilated cardiomyopathy → chronic HF.
• Arrhythmias (VT, VF) → sudden death ⚡.
• Thromboembolism 🩸 (systemic or pulmonary).
• Heart block → pacemaker.

📚 References

• Kindermann I. et al. (2012) JACC
• Cooper LT et al. (2007) Circulation – Biopsy role
• Yu DQ et al. (2014) Exp Ther Med – IVIG in fulminant myocarditis

🧑‍⚕️ Case Examples — Acute Myocarditis

• Case 1 (Viral myocarditis): 🦠 A 22-year-old man develops chest pain and palpitations 1 week after a flu-like illness. ECG shows ST elevation in several leads, but troponin rise is modest compared to STEMI. Echo reveals mildly impaired LV function. Analysis: Viral infection (e.g., Coxsackie, adenovirus) is the commonest cause. Presents like ACS but with disproportionate troponin rise and systemic prodrome. Diagnosis: Acute viral myocarditis. Management: Supportive (rest, avoid strenuous activity for 6 months, beta-blockers/ACEi if LV dysfunction). No role for routine antivirals.
• Case 2 (Autoimmune/immune-mediated myocarditis): 🧬 A 30-year-old woman with systemic lupus erythematosus (SLE) presents with acute shortness of breath, chest pain, and tachycardia. Troponin is elevated, echo shows reduced EF and global hypokinesia. Analysis: Myocardial inflammation as part of autoimmune disease flare. Often indistinguishable from viral causes without biopsy. Diagnosis: Autoimmune myocarditis. Management: Treat with corticosteroids/immunosuppression under specialist guidance, plus supportive heart failure therapy.
• Case 3 (Fulminant myocarditis): 🚨 A 40-year-old man presents with fever, syncope, and cardiogenic shock after a recent viral illness. BP 75/45, tachycardic, CXR shows pulmonary oedema. Echo: severely reduced LV function. Analysis: Life-threatening fulminant myocarditis with rapid progression to cardiogenic shock. Diagnosis: Fulminant myocarditis. Management: ICU admission, inotropes/vasopressors, mechanical circulatory support (IABP/ECMO) if refractory, consider urgent transplant.