Myocarditis

Last updated: July 1, 2022

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Myocarditis is an inflammatory disease of the myocardium that most often affects young individuals and is the cause of approximately 10% of sudden deaths in young adults. The disease is most commonly caused by viral infections (e.g., parvovirus B19, coxsackievirus), but it may also be seen in patients with acute rheumatic fever or autoimmune diseases (e.g., systemic lupus erythematosus, vasculitic syndromes). Patients may be asymptomatic or present with new-onset chest pain, arrhythmias, and/or new-onset heart failure. Severe cardiac inflammation may lead to fulminant myocarditis characterized by cardiogenic shock, hemodynamically significant arrhythmias (e.g., heart block, ventricular tachycardia), and multiorgan failure. Diagnostic testing should include ECG, inflammatory markers and cardiac biomarkers, transthoracic echocardiography (TTE), and possibly diagnostic confirmation with endomyocardial biopsy. Management of myocarditis involves supportive measures and targeted treatment of any underlying disease as indicated. Most adults with viral myocarditis make a full recovery, but there is a small risk of the condition progressing to dilated cardiomyopathy. The prognosis is especially poor for infants.

The exact incidence is unknown.

  • 1–5% of viral infections are estimated to have cardiac involvement.
  • Often occurs in young patients (average age ∼ 40 years)
  • In ∼ 10% of sudden deaths in young adults, myocarditis is diagnosed in the post-mortem examination. [1]

Epidemiological data refers to the US, unless otherwise specified.

Infectious [2]

Noninfectious [3]

The clinical manifestation of myocarditis is heterogeneous and nonspecific, ranging from asymptomatic courses to fulminant cardiac decompensation.
References:[3][5]

Approach [1][6][7]

Suspect myocarditis in patients without ASCVD risk factors who present with chest pain, arrhythmias, and/or heart failure not explained by another disease.

12-lead ECG [1][7]

ECG findings in myocarditis are often abnormal but nonspecific, and may include :

Laboratory studies [6][7]

Obtain routine studies for all patients. Additional studies to determine the underlying cause of myocarditis should be guided by clinical suspicion.

Imaging [7][9][10]

Initial imaging

Advanced imaging [6][7][10]

Cardiac MRI should not delay endomyocardial biopsy in patients with fulminant myocarditis or subacute presentation who have not responded to standard care for arrhythmia and/or congestive heart failure within 1–2 weeks. [6]

Endomyocardial biopsy (EMB) [6][7][8][11]

EMB is considered the gold standard test for diagnostic confirmation and can identify the underlying cause of myocarditis.

The differential diagnoses listed here are not exhaustive.

Approach [1][7][8][12]

For hemodynamically unstable patients, see “Management of fulminant myocarditis.”

  • Admit for inpatient management for continuous cardiac monitoring.
  • Start symptomatic treatment as needed.
  • Identify and treat the underlying cause.
    • Review and consider stopping medications that can cause toxic myocarditis. [6][9]
    • Initiate targeted therapy as indicated under specialist guidance (e.g., rheumatology).
  • Recommend avoiding aerobic activity for 3–6 months after diagnosis.
  • Follow-up at regular intervals using clinical assessment, ECG, and TTE findings.

Symptomatic treatment [1][8][11]

Use NSAIDs with caution as they can increase sodium retention, exacerbate renal hypoperfusion, and may increase mortality in patients with myocarditis. [1][6]

Treatment of the underlying cause [1][11]

All treatment should be guided by a specialist.

Management of fulminant myocarditis [6]

Fulminant myocarditis is a rare and life-threatening syndrome of severe myocardial inflammation.

Immediately consult cardiology and initiate management of acute heart failure and cardiogenic shock. Maintain a low threshold for beginning treatment of refractory acute heart failure (e.g., with mechanical circulatory support). [13]

References:[5]

We list the most important complications. The selection is not exhaustive.

  1. Kindermann, Barth, Mahfoud, et al.. Update on Myocarditis. J Am Coll Cardiol. 2012; 59 (9). doi: 10.1016/j.jacc.2011.09.074 . | Open in Read by QxMD
  2. Cooper LT. Etiology and pathogenesis of myocarditis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/etiology-and-pathogenesis-of-myocarditis?source=search_result&search=myocarditis&selectedTitle=4~150.Last updated: March 21, 2016. Accessed: December 21, 2016.
  3. Cooper LT. Myocarditis. N Engl J Med. 2009; 360 (15): p.1526-1538. doi: 10.1056/nejmra0800028 . | Open in Read by QxMD
  4. Kang M, An J. Viral Myocarditis. StatPearls. 2020 .
  5. Cooper LT. Clinical manifestations and diagnosis of myocarditis in adults. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-myocarditis-in-adults?source=search_result&search=myocarditis&selectedTitle=1~150.Last updated: May 20, 2016. Accessed: December 22, 2016.
  6. Kociol RD, Cooper LT, Fang JC, et al. Recognition and Initial Management of Fulminant Myocarditis: A Scientific Statement From the American Heart Association.. Circulation. 2020; 141 (6): p.e69-e92. doi: 10.1161/CIR.0000000000000745 . | Open in Read by QxMD
  7. Caforio AL, Pankuweit S, Arbustini E, et al. Current state of knowledge on aetiology, diagnosis, management, and therapy of myocarditis: a position statement of the European Society of Cardiology Working Group on Myocardial and Pericardial Diseases.. Eur Heart J. 2013; 34 (33): p.2636-48, 2648a-2648d. doi: 10.1093/eurheartj/eht210 . | Open in Read by QxMD
  8. Bozkurt B, Colvin M, Cook J, et al. Current Diagnostic and Treatment Strategies for Specific Dilated Cardiomyopathies: A Scientific Statement From the American Heart Association. Circulation. 2016; 134 (23). doi: 10.1161/cir.0000000000000455 . | Open in Read by QxMD
  9. Blauwet LA, Cooper LT. Myocarditis. Prog Cardiovasc Dis. 2010; 52 (4): p.274-288. doi: 10.1016/j.pcad.2009.11.006 . | Open in Read by QxMD
  10. Rajiah P, Kirsch J, Bolen MA, et al. ACR Appropriateness Criteria® Nonischemic Myocardial Disease with Clinical Manifestations (Ischemic Cardiomyopathy Already Excluded). J Am Coll Radiol. 2021; 18 (5): p.S83-S105. doi: 10.1016/j.jacr.2021.01.019 . | Open in Read by QxMD
  11. Tschöpe C, Ammirati E, Bozkurt B, et al. Myocarditis and inflammatory cardiomyopathy: current evidence and future directions.. Nat Rev Cardiol. 2021; 18 (3): p.169-193. doi: 10.1038/s41569-020-00435-x . | Open in Read by QxMD
  12. Tschöpe C, Cooper LT, Torre-Amione G, Van Linthout S. Management of Myocarditis-Related Cardiomyopathy in Adults.. Circ Res. 2019; 124 (11): p.1568-1583. doi: 10.1161/CIRCRESAHA.118.313578 . | Open in Read by QxMD
  13. Dancea AB. Myocarditis in infants and children: A review for the paediatrician. Paediatr Child Health. 2001; 6 (8): p.543-545.
  14. Fricke L. Diagnosis and management of accommodative esotropia. Clin Exp Optom. 2006; 89 (5): p.325-331. doi: 10.1111/j.1444-0938.2006.00059.x . | Open in Read by QxMD

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