Pathological autoantibodies in cardiomyopathy.

Myocardial dilatation and dysfunction in the absence of significant coronary heart disease has been termed "idiopathic" dilated cardiomyopathy (iDCM), which--according to the 1995 task force report on the classification of cardiomyopathies-besides genetic, toxic or infectious causes also includes immune-mediated heart muscle damage in the spectrum of putative DCM etiologies. Incremental research on this topic particularly in the past few years has significantly contributed evidence to the hypothesis that autoimmune reactions against certain myocyte antigens may play a pivotal role in the initiation and/or progression of DCM. Recent transfer experiments in animals (mostly rodents) performed by various groups throughout the world and some preliminary clinical data even indicate that a few of these autoantibodies are indeed "pathogenic", inferring that they can actually cause cardiac dysfunction and heart failure by their own. Dependent on the individual genetic predisposition such harmful autoimmune reactions are supposed to emerge as a consequence of heart muscle damage induced by viral triggers, ischemia or exposure to cardiotoxins leading to myocyte apoptosis (and/or necrosis) and subsequent liberation of a "critical amount" of self-antigens previously hidden to the immune system. The following article will summarize the so far available evidence for an implication of a confined number of harmful autoantibodies directed against specific cardiac antigens in the pathogenesis of DCM.