Historical Terminology, Classifications, and Present Definition of DCM.

Dilated cardiomyopathy (DCM) is defined by the presence of left ventricular (LV) dilation and systolic dysfunction in the absence of abnormal loading conditions or coronary artery disease sufficient to cause the LV systolic impairment. In the last years, advances in pathophysiology, pathology, biomarkers, genetics and molecular medicine, echocardiography, and cardiac magnetic resonance have allowed an evolution from an etiological to a morphological and then to a morphofunctional classification of the disease. Familial forms account for the 40% of cases, and thanks to the recent discoveries in the genetic field, clinicians have the opportunity but also the responsibility to provide an etiological diagnosis, stratify the risk, and treat patients with the best strategy available. Nowadays the etiologic characterization has dramatically improved so that it is possible to understand the etiologic basis of many so-called idiopathic heart muscle disease. A step toward a comprehensive DCM classification and an attempt to reconcile clinic with genetic in the complexity of the disease is genotype-phenotype correlation, with its prognostic implication in clinical practice. In this chapter will be discussed the historical evolution of DCM classification, and an overview of the main issues discussed in the next sections will be given.