Clinical Subject Page
Myocarditis
Also called
Inflammatory Cardiomyopathy
ICD-10
I40.9
Specialty
Cardiology
Onset
Acute & Chronic
Reviewed
July 2026
On This Page
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OverviewOverview
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Etiology & Risk FactorsEtiology & Risk Factors
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PathophysiologyPathophysiology
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Clinical PresentationClinical Presentation
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History TakingHistory Taking
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InvestigationsInvestigations
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DiagnosisDiagnosis
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ManagementManagement
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ComplicationsComplications
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PrognosisPrognosis
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Key Points / Clinical PearlsKey Points / Clinical Pearls
Overview
Myocarditis is an inflammatory disease of the myocardium, most commonly caused by viral infections, leading to myocardial injury, impaired cardiac function, arrhythmias, and, in severe cases, heart failure.
Teaching point
Myocarditis should be suspected in patients with recent viral illness who develop chest pain, heart failure, or unexplained arrhythmias.
Etiology & Risk Factors
Etiology
- Viral infections (most common)
- Bacterial infections
- Autoimmune diseases
- Drug-induced hypersensitivity
- Toxins
- Giant cell myocarditis
- Sarcoidosis
Risk Factors
- Recent viral illness
- Autoimmune disease
- Immunosuppression
- Young age
- Exposure to cardiotoxic drugs
- Family history of autoimmune disease
Pathophysiology
Viral infection / Autoimmune injury
↓
Myocardial inflammation
↓
Myocyte injury & necrosis
↓
↓ Myocardial contractility
↓
LV systolic dysfunction
↓
Heart failure + Arrhythmias
↓
Dilated cardiomyopathy (chronic cases)
Clinical Presentation
Symptoms
- Chest pain
- Dyspnea
- Fatigue
- Palpitations
- Syncope
- Fever
- Recent viral illness
Signs
- Tachycardia
- S3 gallop
- Signs of heart failure
- Arrhythmias
- Hypotension (severe cases)
Important Note
Chest pain with elevated troponin and normal coronary arteries should raise suspicion for myocarditis.
History Taking
Key Questions
- Recent viral illness?
- Chest pain?
- Shortness of breath?
- Palpitations?
- Syncope?
- Fever?
- Autoimmune disease?
- New medications?
- Toxin exposure?
Red Flags
- Cardiogenic shock
- Sustained ventricular arrhythmias
- Syncope
- Acute heart failure
- Sudden cardiac arrest
Investigations
Laboratory
- CBC
- CRP/ESR
- Troponin
- BNP/NT-proBNP
- Viral studies (selected patients)
ECG
- Sinus tachycardia
- ST-T changes
- Arrhythmias
- AV block
Imaging
- Echocardiography
- Cardiac MRI (preferred non-invasive test)
- Chest X-ray
Additional Tests
- Endomyocardial biopsy (gold standard in selected patients)
- Coronary angiography (to exclude ACS)
Diagnosis
Diagnosis is based on:
- Clinical suspicion
- Elevated cardiac biomarkers
- ECG abnormalities
- Cardiac MRI findings
- Endomyocardial biopsy in selected cases
Management
Supportive Care
- Rest and activity restriction
- Treat heart failure if present
- Manage arrhythmias
Medications
- ACE inhibitor/ARB/ARNI
- β-blocker (when stable)
- Diuretics
- MRA
- Immunosuppressive therapy (selected autoimmune cases)
Advanced Therapy
- Mechanical circulatory support
- Heart transplantation (fulminant myocarditis)
Complications
- Heart failure
- Dilated cardiomyopathy
- Ventricular arrhythmias
- AV block
- Cardiogenic shock
- Sudden cardiac death
Prognosis
- Many patients recover completely.
- Fulminant myocarditis requires urgent treatment but may recover with appropriate support.
- Persistent inflammation may progress to dilated cardiomyopathy.
- Prognosis depends on the cause and severity.