Autoimmune abnormalities, as well as
viral infection and genetic abnormalities, appear to be major predisposing factors for
dilated cardiomyopathy (DCM). Abnormalities of cell-mediated immunity are mainly involved in the onset of
cardiomyopathy secondary to
myocarditis. However, various antimyocardial
antibodies are detected in the serum of patients with DCM. The appearance of these
antibodies was considered to be an epiphenomenon associated with myocyte injury resulting from
myocarditis, but recent findings have suggested that at least some of them are directly related to the pathophysiology of DCM. In particular, an
autoantibody targeting the beta1-adrenergic receptor that exhibits an agonist-like effect is related to the persistent myocardial damage resulting in DCM and provides substrates for fatal ventricular arrhythmias. In addition, an antibody for the
muscarinic M2 receptor is related to
atrial fibrillation, an antibody targeting Na-K-
ATPase is closely related to
sudden cardiac death as a result of fatal ventricular arrhythmias, and an
autoantibody for
troponin I increases the L-type
calcium current and is related to the myocardial damage. Based on these findings, immunoadsorption
therapy was developed to remove such
autoantibodies in patients with refractory
heart failure as a result of DCM.