Dilated cardiomyopathy (DCM) is an autoimmune-related cardiac disease for which apheresis treatment is indicated. DCM is defined as a group of diseases characterized by progressive contraction failure and dilation of the left ventricle (or both ventricles) which is not caused by abnormal stress or coronary artery diseases [1]. Patients with DCM can present with heart failure caused by contractile dysfunction and can sometimes die suddenly from arrhythmia. Idiopathic DCM is diagnosed in the absence of the evident cause of cardiac dysfunction, such as coronary artery stenosis or secondary cardiomyopathy, as seen by coronary angiography or cardiac biopsy. The prevalence and total number of patients with idiopathic DCM in Japan—14.0 per 100,000 population and 17,700, respectively—were estimated in an epidemiological nationwide survey for patients conducted in 1999 [2].