II. Epidemiology

  1. Ages
    1. Children: Age <2 years old
    2. Adolescents: Age 14 to 18 years old
    3. Adults: Ages 20 to 40 years old

III. Causes

  1. See Secondary Cardiomyopathy (includes Viral Myocarditis Causes)

IV. Associated Conditions

V. Precautions

  1. Myocarditis is a clinical diagnosis with no single, definitive noninvasive diagnostic test
  2. Exercise a high level of suspicion in atypical presentations of common acute cardiopulmonary diseases

VI. Symptoms

  1. Presentations vary widely
    1. Most cases are mild and asymptomatic
    2. However, can be severe and life-threatening (especially in children)
      1. May be responsible for up to 20% of unexplained cardiac death in young adults
  2. Influenza-like illness presentation is common
    1. Fever (Viral Myocarditis)
    2. Fatigue
    3. Myalgias
    4. Arthralgias
    5. Malaise
  3. Chest symptoms
    1. Palpitations
    2. Pleuritic Chest Pain
    3. Sinus Tachycardia out of proportion to other findings (or other Dysrhythmia)
    4. Dyspnea on exertion
    5. Heart Block (Lyme Disease, Sarcoidosis, giant cell Myocarditis)
      1. Bradycardia
      2. Syncope
  4. Symptoms related to secondary events and decompensation
    1. Myocardial Infarction
    2. Acute Dysrhythmia
    3. Congestive Heart Failure or Cardiogenic Shock
  5. Infant and young child presentation
    1. Poor feeding
    2. Lethargy
    3. Respiratory distress (Tachypnea, intercostal retractions, grunting)
    4. Gastrointestinal Symptoms (Nausea, Vomiting or Abdominal Pain)

VII. Signs

  1. Pericardial Friction Rub
  2. Loud S3 Gallop
  3. Sinus Tachycardia (or other fast Dysrhythmia)
    1. Out of proportion to other causes (e.g. beyond what would be expected with fever alone)
  4. Weak pulses

VIII. Labs

  1. Complete Blood Count
    1. Leukocytosis
  2. Troponin I increased
    1. Very high Troponins may be seen in Myocarditis (higher than in Acute Coronary Syndrome)
    2. Often normal, especially in children
  3. Brain Natriuretic Peptide (BNP, ntBNP) increased
  4. Thyroid Stimulating Hormone (TSH)
  5. Lactic Acid
  6. Venous Blood Gas (VBG)
  7. Serum Aspartate Aminotransferase
    1. Nonspecific increase is also seen with Kawasaki Disease
  8. Acute phase reactants
    1. Erythrocyte Sedimentation Rate (ESR) >60 mm/h
    2. C-Reactive Protein (CRP) increased

IX. Diagnostics: Electrocardiogram

  1. Sinus Tachycardia
  2. QRS abnormality (associated with worse prognosis)
    1. Low-voltage QRS Complexes
    2. Wide QRS Complex
    3. Pathologic Q Waves
  3. Diffuse EKG changes (all leads)
  4. Saddle-shaped ST Segment Elevation progresses to T Wave Inversion
  5. EKG normalizes in 2 months
  6. Conduction abnormalities may occur
    1. Heart Block including complete Heart Block (Lyme Disease, Sarcoidosis, giant cell Myocarditis)

X. Imaging

  1. Chest XRay
    1. Cardiomegaly in 50% cases
    2. Pulmonary vascular congestion
    3. Pleural Effusions
  2. Echocardiogram
    1. Dilated Cardiomyopathy
    2. Left Ventricular Dilation
    3. Decreased ejection fraction
  3. Cardiac MRI
    1. Most accurate non-invasive imaging modality to diagnose Myocarditis
    2. Assess LV Ejection fraction, wall thickness, ventricle size, tissue injury
  4. Endomyocardial Biopsy Indications
    1. Fulminant myocardititis
    2. Acute Dilated Cardiomyopathy with VT or complete Heart Block refractory to standard management

XII. Management

  1. Management is typically symptomatic
  2. Severe, Fulminant Myocarditis requires Critical Care
    1. Hypotension
    2. Severe Congestive Heart Failure
    3. Cardiogenic Shock
    4. Complete Heart Block
  3. Specific management may be based on underlying cause
    1. Lyme Disease
    2. Mycobacterium tuberculosis
    3. Trypanosoma cruzi
  4. Disposition is based on severity of clinical presentation
    1. Initial inpatient management is waranted in severe cases
    2. Most acute Myocarditis in young children are admitted, often to Intensive Care unit
  5. Young children may present in severe CHF, and require intensive management
    1. Endotracheal Intubation
    2. Inotropic support (Dopamine, Dobutamine, Milrinone)
    3. Consider Diuretics (Furosemide) if hypertensive and Fluid Overload
    4. Afterload reduction
    5. Dysrhythmia management (e.g. Amiodarone, Lidocaine)
    6. Transfer to pediatric Intensive Care with ECMO capability
  6. Various agents have been used historically, especially for Viral Myocarditis (e.g. coxsachievirus)
    1. IV Ig (effective in Kawasaki's Disease, but not in Viral Myocarditis)
      1. Robinson (2015) Cochrane Database Syst Rev (5): CD004370 [PubMed]
    2. Immunosuppresants (Corticosteroids, Cyclosporine) have not been effective in Viral Myocarditis
      1. Chen (2013) Cochrane Database Syst Rev (1):CD004471 [PubMed]

XIII. Complications

XIV. References

  1. Claudius, Behar, Salway and Kearl in Herbert (2018) EM:Rap 18(5): 1-3
  2. DeMeester and Weinstock in Swadron (2022) EM:Rap 22(5): 15-7
  3. Sharrief in Herbert (2012) EM:Rap 12(5): 8
  4. Klauer (2013) Congestive Heart Failure and Myocarditis, EM Bootcamp, CEME
  5. Pacheco and Rawani-Patel (2019) Crit Dec Emerg Med 33(5): 3-11

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Related Studies

Ontology: Myocarditis (C0027059)

Definition (CHV) inflammation of the heart muscle
Definition (NCI) Inflammation of the muscle tissue of the heart.
Definition (NCI_CTCAE) A disorder characterized by inflammation of the muscle tissue of the heart.
Definition (MSH) Inflammatory processes of the muscular walls of the heart (MYOCARDIUM) which result in injury to the cardiac muscle cells (MYOCYTES, CARDIAC). Manifestations range from subclinical to sudden death (DEATH, SUDDEN). Myocarditis in association with cardiac dysfunction is classified as inflammatory CARDIOMYOPATHY usually caused by INFECTION, autoimmune diseases, or responses to toxic substances. Myocarditis is also a common cause of DILATED CARDIOMYOPATHY and other cardiomyopathies.
Definition (CSP) inflammation of the muscular walls of the heart.
Concepts Disease or Syndrome (T047)
MSH D009205
ICD9 429.0
ICD10 I51.4
SnomedCT 155380004, 251060004, 195119007, 50920009
English Myocarditides, Myocarditis NOS, Myocarditis, unspecified, Myocarditis, myocarditis (diagnosis), myocarditis, Myocarditis [Disease/Finding], Myocarditis NOS (disorder), Myocardial inflammation (finding), MYOCARDITIS, Myocarditis (disorder), inflammation; myocardium, myocardium; inflammation, Myocarditis, NOS, Myocardial inflammation
French MYOCARDITE, Myocardite, non précisée, Myocardite SAI, Myocardite
Portuguese MIOCARDITE, Miocardite NE, Miocardite
Spanish MIOCARDITIS, Miocarditis NEOM, Miocarditis no especificada, miocarditis, SAI, inflamación miocárdica (hallazgo), miocarditis, SAI (trastorno), Myocarditis NOS, inflamación miocárdica, miocarditis (trastorno), miocarditis, Miocarditis
Dutch myocarditis, niet-gespecificeerd, myocarditis NAO, myocard; ontsteking, ontsteking; myocard, Myocarditis, niet gespecificeerd, myocarditis, Myocarditis
German Myokarditis NNB, Myokarditis, unspezifisch, MYOCARDITIS, Myokarditis, nicht naeher bezeichnet, Myokarditis
Italian Miocardite NAS, Miocardite non specificata, Miocardite
Japanese 心筋炎NOS, 心筋炎、詳細不明, 心筋炎, シンキンエンショウサイフメイ, シンキンエン, シンキンエンNOS
Swedish Hjärtmuskelinflammation
Czech myokard - zánět, zánět srdečního svalu, myokarditida, Myokarditida, Myokarditida NOS, Myokarditida, blíže neurčená
Finnish Sydänlihastulehdus
Korean 상세불명의 심근염
Polish Zapalenie mięśnia sercowego
Hungarian Myocarditis, Myocarditis, nem meghatározott, Myocarditis k.m.n.
Norwegian Hjertemuskelbetennelse, Myokarditt

Ontology: Viral carditis (C0151328)

Concepts Disease or Syndrome (T047)
ICD10 B33.2 , B33.20
SnomedCT 186755002
German Karditis durch Viren
Korean 바이러스 심장염
English Viral carditis, unspecified, Viral carditis, Viral carditis (disorder), carditis; viral (manifestation), virus; carditis (manifestation)
Spanish carditis vírica, carditis viral (trastorno), carditis viral
Dutch carditis; virus, virus; carditis, Virale carditis

Ontology: Dilated cardiomyopathy secondary to viral myocarditis (C0264797)

Concepts Disease or Syndrome (T047)
ICD10 B33.24
SnomedCT 30496006
English Viral cardiomyopathy, viral cardiomyopathy, Dilated cardiomyopathy secondary to viral myocarditis, Dilated cardiomyopathy secondary to viral myocarditis (disorder)
Spanish Cardiomiopatía vírica, miocardiopatía dilatada secundaria a miocarditis virósica, miocardiopatía dilatada secundaria a miocarditis viral (trastorno), miocardiopatía dilatada secundaria a miocarditis viral, miocardiopatía dilatada secundaria a miocarditis vírica
Portuguese Cardiomiopatia viral
Dutch virale cardiomyopathie
Italian Cardiomiopatia virale
French Cardiomyopathie virale
German Virus-induzierte Kardiomyopathie
Czech Virová kardiomyopatie
Japanese ウイルスセイシンキンショウ, ウイルス性心筋症
Hungarian Vírusos cardiomyopathia

Ontology: Viral myocarditis (C0276138)

Concepts Disease or Syndrome (T047)
ICD10 B33.22
SnomedCT 89141000
Italian Miocardite virale, Miocardite virale NAS
Dutch myocarditis viraal NAO, myocarditis; viraal, viraal; myocarditis, virale myocarditis
French Myocardite virale SAI, Myocardite virale
German Myokarditis viral NNB, virale Myokarditis
Portuguese Miocardite viral NE, Miocardite viral
Spanish Miocarditis vírica NEOM, miocarditis virósica, miocarditis vírica, miocarditis viral (trastorno), miocarditis viral, Miocarditis vírica
Japanese ウイルス性心筋炎, ウイルス性心筋炎NOS, ウイルスセイシンキンエンNOS, ウイルスセイシンキンエン
Czech Virová myokarditida, Virová myokarditida NOS
English Myocarditis viral NOS, viral myocarditis, myocarditis viral, Viral myocarditis, Viral myocarditis (disorder), myocarditis; viral, viral; myocarditis, Viral myocarditis, NOS
Hungarian vírusos myocarditis, Viralis myocarditis k.m.n.