Giant cell myocarditis

In 1900, the Dresden physician Carl Ludwig Alfred Fiedler (1835-1921) described for the first time an idiopathic form of myocarditis, which was named after him as Fiedler's myocarditis.

Giant cell myocarditis is an inflammation of the myocardium characterized by infiltration of giant multinucleated cells and lymphocytes without detection of viruses or other pathogens (Schwimmbeck 2015).

Giant cell myocarditis is a very rare disease. It occurs preferentially in young, previously healthy people (Magerkurth 2008)

Giant cell myocarditis is an etiologically unexplained disease (Kohl 2000). Not infrequently, an association with autoimmune diseases, thymoma and inflammatory intestinal diseases is observed. Studies on affected patients and on the Lewis rat model suggest that the disease is mediated by T-lymphocytes (Cooper 2012).

Acute left-thoracic pain may occur, which makes one think of a myocardial infarction. Sometimes, however, there are also, at least initially, unspecific symptoms which later show symptoms of acute dilated cardiomyopathy. However, this then turns out to be refractory to the treatment according to the guidelines (Kühl 2012).

Common symptoms are:

• signs of heart failure
• bradycardic and/or tachycardic cardiac arrhythmia (Kohl 2000)
• ventricular arrhythmias (according to the latest studies, they are caused by a cytokine-induced change in desmosomal protein expression (Cooper 2012)

Echocardiography: There is marked dilatation of the left ventricle (Schwimmbeck 2015).

Chest X-ray: There is usually an enlargement of the cardiac shadow due to dilatation of the left ventricle (Schwimmbeck 2015).

If the symptoms of acute dilated cardiomyopathy prove to be refractory even after guideline-based treatment, giant cell myocarditis should be suspected (Cooper 2012).the diagnosis can only be confirmed by myocardial biopsy (Kohl 2000)

ECG

• Ventricular tachycardia (Cooper 2012)
• higher grade AV-blockings (swimming pool 2015)
• ventricular arrhythmias (swimming pool 2015)

Endomyocardial biopsy

Endomyocardial biopsy is required for the diagnosis of giant cell myocarditis, as differential diagnosis - especially in relation to microvascular ischemia - can sometimes be difficult. The puncture can be performed either left or right ventricularly, since no significant difference can be detected with regard to valence. It is only important to take several biopsies, also from the septum area (Schwimmbeck 2015).

Histology

• Detection of numerous giant multinuclear cells
• eosinophil granulocytes
• T lymphocytes
• Macrophages (Kandolf 2011)

pronounced necrobiotic changes in the myocardium (Kandolf 2011)

Immunohistologically, the giant cells originate from CD68 - positive precursor cells of macrophages and are CD68 - positive (Kandolf 2011)

• Cardiac sarcoidosis: in this disease, the granulomas can also be detected histologically in other organs (Matejic 2010). However, cardiac sarcoidosis represents a difficult differential diagnosis overall, because it is also characterized by C68 - positive giant cells. However, no necrosis of myocytes and only rarely eosinophilic granulocytes are found in sarcoidosis (Kandolf 2011)
• Eosinophilic myocarditis: it is also a very difficult differential diagnosis; therefore, in case of peripheral eosinophilia, it should be excluded:
• a vasculitis (e.g. Churg-Strauss syndrome, polyarteritis nodosa etc)
• malignant diseases, especially leukemia, lung carcinoma, lymphoma, melanoma etc.
• Löffler endocarditis (in this case, both endocardial and myocardial tissue damage is seen due to eosinophilic granulocytes showing secondary thrombus formation as part of the damage to the endocardium (Kandolf 2011)
• diffuse microvascular ischemia (Schwimmbeck 2015).

General:

Before starting treatment with immunosuppressive drugs, a viral genesis must be reliably excluded (Schwimmbeck 2015).

In patients treated with cyclosporine + glucocorticoids, or azathioprine or muromonab-CD3, a prolonged graft-free survival was already demonstrated in 2007 (12.6 months versus 3 months [Reinhardt 2007]).

Since there is evidence that giant cell myocarditis is mediated by T-lymphocytes, a therapy to reduce T-cell function may be appropriate. However, further investigations are necessary (Cooper 2012).

The currently recommended treatment of giant cell myocarditis consists of an aggressive therapy with anti-CD3 antibodies, ciclosporin and cortisone and lasts a total of 12 months (Cooper 2012).

Therapy proposal (Kühl 2012):

• anti-CD3 - antibodies (OKT 3): 5 mg /d i.v. over 7 days; 10 mg /kg bw over 3 days (cave initial hypotension!)
• Ciclosporin: adapted dosage up to a trough level between 100 - 120 µg / mL for a total of at least 12 months
• Methylprednisolone: 1mg / kg bw for 2 weeks, then reduction by 10 mg / 4 weeks each; then every 2 weeks reduction of the dose by 10 mg each until the maintenance dose of 5 mg - 10 mg / d; therapy with cortisone should be carried out for at least 12 months in total.
• Pantoprazole 20 mg / d
• Calcium substitution 1 x 1 g/d

There should be regular checks of liver and kidney values (Ciclosporin) as well as blood sugar and differential blood count (methylprednisolone) (Kühl 2012).

Giant cell myocarditis has a high mortality rate and is therefore a very serious disease. The average survival time without treatment is about 3 months (Kohl 2000).

In about 70% of patients a heart transplantation is necessary within one year (Magerkurth 2008).

Even in transplantation recurrences are not uncommon (Kohl 2000). They occur in 20% - 25% of cases (Cooper 2012).

Since this is a rare disease, it is recommended to contact centres that have treatment protocols (Herold 2018).

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