Giant-cell myocarditis (GCM) is a rare form of myocarditis mostly with a dramatic course and life-threatening complications.

GCM is characterized by the histopathological finding of giant multinuclear cells, infiltration with eosinophils and T lymphocytes and necrosis of cardiomyocytes.

Giant cells are localized primarily at the edge of the myocardial necrosis [48]. In contrast to sarcoidosis, in GCM there are observed smaller fibrous changes and a minimal number of irregularly shaped granulomas [49, 50]. The presence of bordered granulomas confirms rather the diagnosis of sarcoidosis [51]. These changes do not have to in some cases affect just the ventricular myocardium, but also the myocardium of atriums [48]. GCM is definitively confirmed just with EMB.

GCM prevalence is very low. In the USA, the disease is even written in the list of rare disease [52]. In a retrospective study of patients who underwent EMB, GCM was confirmed just in 4 from 851 performed biopsies [53]. Specifically, in children, its prevalence is even lower. Up to the year 2006, there were just 14 documented cases [54] with the prevalence of females.

Pathogenesis of GCM in not still quite clear. Most likely, it arises on the basis of autoimmune disorder [50]. Up to 20 % of patients had a simultaneous presence of an autoimmune disease (for example Crohn´s disease, ulcerative colitis, autoimmune thyroiditis or myasthenia), [55, 56].

It is often a fatal disease presenting in fulminant form and even with a transition to the cardiogenic shock. In the research of GCM from 1997, 75 % of patients presented with heart failure, 14 % with ventricular tachycardia and 5 % with complete AV block [55]. Simultaneously, the effectiveness of immunosuppressants and corticosteroids therapy, which remain the main therapy of GCM up to the present, was researched. A prolongation of the median of the survival was described in patients with this therapy (12,3 months) in comparison with patients treated just with the heart failure therapy (3 months). The mortality rate of patients or the necessity of heart transplant was even up to 89 % [55]. Similar results were observed even in a study from 2003 with the 5-year survival rate of 22 % including patients without the necessity of the heart transplant [49].

In the Finnish study published in 2012, the 5-year survival rate was 52 % also including patients without the necessity of heart transplant [56].

The relapse of GCM was recorded in 20 to 25 % of patients after the heart transplant. It was mostly suppressed by higher doses of immunosuppressive drugs [54, 57].

Combined immunosuppressive therapy includes according to the resources usually the combination of corticosteroids with azathioprine or mycophenolate and cyclosporine. In the most of patients, ICD is indicated because of a high risk of death due to malignant arrhythmias [56, 57]. There are also many patients where the heart transplant is the only therapeutic option even though there are described some cases when patients were stabilized just with the immunosuppressive and heart failure therapy [57].

Author of the opening picture: Gregory Marcus, MD, MAS, FACC

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References:

48) J., DAVIES a et al. Idiopathic giant cell myocarditis-a distinctive clinico-pathological entity. British Heart Journal [online]. 1975, 1975(37), 192-195 [cit. 2017-02-05].

49) OKURA a et al. A clinical and histopathologic comparison of cardiac sarcoidosis and idiopathic giant cell myocarditis. Journal of the American College of Cardiology [online]. 2003, 41(2), 322 [cit. 2017-02-05].

50) KUBÁNEK a VOSKA L. Obrovskobuněčná myokarditida a sarkoidóza srdce – update 2015. Kardiologická revue – Interní medicína. 17(4), 295-299.

51) T., JR., COOPER. Chapter 17: Idiopathic Giant Cell Myocarditis. In: L.T., JR., COOPER, ed. Myocarditis: From Bench to Bedside. USA: Humana Press, 2003. pp. 405-420. ISBN 1-58829-112-X.

52) Giant Cell Myocarditis. National Organization for Rare Disorders [online]. USA: -, 2006 [cit. 2017-02-07].

53) K., BENNETT a et al. Evaluation of the Role of Endomyocardial Biopsy in 851 Patients With Unexplained Heart Failure From 2000–2009. Circulation: Heart Failure [online]. 2013, 2013(6), 676-684 [cit. 2017-02-05].

54) D., BINHUTI a et al. Cardiac Transplantation for Pediatric Giant Cell Myocarditis. Journal of Heart Lung Transplant. 2006, 2006(25), 474-478.

55) T., JR., COOPER a et al. IDIOPATHIC GIANT-CELL MYOCARDITIS — NATURAL HISTORY AND TREATMENT. The New England Journal of Medicine. 1997, 1997(336), 1860-1866.

56) KANDOLIN a et al. Diagnosis, Treatment, and Outcome of Giant-Cell Myocarditis in the Era of Combined Immunosuppression. Circulation: Heart Failure [online]. 2013, 2013(6), 15-22 [cit. 2017-02-05].

57) A., CHAUDHRY a et al. Modern day management of giant cell myocarditis. International Journal of Cardiology. 2015, 2015(178), 82-84.