[Incidental Diagnosis of Giant Cell Myocarditis at Open Heart Surgery:Report of Case].

Giant cell myocarditis (GCM) is one of the rare diseases that cause fatal heart failure and suspected to be associated with autoimmune disorder. There are few reports that the patients of GCM live long because of their progressive heart failure. We report a rare case of patient who was suspected two long hospitalizations due to heart failure in her childhood and peripartum period, and incidentally diagnosed with GCM by myocardial biopsy performed at the aortic valve replacement and mitral annuloplasty for severe aortic valve regurgitation and moderate mitral regurgitation.