Giant Cell Myocarditis

This week we had a fantastic discussion led by Dr. Padilla about a case of recurrent symptomatic ventricular tachycardia eventually diagnosed as Giant Cell Myocarditis.

Based on symptoms of palpitations, the differential is broad and the workup dependent on clinical features and level of concern. In this case, the key piece of data that we obtained was the ambulatory ECG, which revealed marked episodes of recurrent ventricular tachycardia, longer than 1 minute!

 Characteristic ECG findings, courtesy of https://lifeinthefastlane.com/ecg-library/ventricular-tachycardia/

Characteristic ECG findings, courtesy of https://lifeinthefastlane.com/ecg-library/ventricular-tachycardia/

We reviewed the different possible types of ambulatory monitoring and their indications:

 Different ambulatory monitoring modalities for arrhythmia, courtesy of https://www.bcmj.org

Different ambulatory monitoring modalities for arrhythmia, courtesy of https://www.bcmj.org

The differential of ventricular tachycardia is broad, but as part of the workup, we like to think through the following framework:

  • Structural heart disease
    • Past ischemia, scarring
    • Cardiomyopathies
    • Infiltrative heart disease
  • Inherited disorders
    • Brugada Syndrome
    • Arrhyhtmogenic right ventricular dysplasia
    • Congenital Long QT
    • Hypertrophic Cardiomyopathy
  • Idiopathic
  • "Other"
    • Includes acute ischemia, metabolic/electrolyte causes, drugs/medication, hypoxia

In this case, the patient underwent cardiac MRI, which revealed late gadolinium enhancement and myocardial strain, characteristic of giant cell myocarditis

Briefly, giant cell myocarditis is a rare disorder attributed to T-cell mediated autoimmunity, characterized by biventricular enlargement, refractory ventricular arrhythmias with progression to cardiac shock.

Though there are characteristic findings on cardiac MRI, an endomyocardial biopsy is diagnostic.

Patients are treated with immunosuppression, with referral to cardiac transplantation if appropriate.

References:
http://circ.ahajournals.org/content/129/17/e467
https://lifeinthefastlane.com/ecg-library/ventricular-tachycardia/
https://www.bcmj.org/articles/ambulatory-electrocardiography-contribution-norman-jefferis-holter
https://www.uptodate.com/contents/monomorphic-ventricular-tachycardia-in-the-absence-of-apparent-structural-heart-disease?topicRef=6835&source=see_link