Alternative definition : KEGG: Dilated cardiomyopathy (DCM) is a heart muscle disease characterised by dilation
and impaired contraction of the left or both ventricles that results in progressive
heart failure and sudden cardiac death from ventricular arrhythmia. Genetically inherited
forms of DCM (familial DCM) have been identified in 25-35% of patients presenting
with this disease, and the inherited gene defects are an important cause of familial
DCM. The pathophysiology may be separated into two categories: defects in force generation
and defects in force transmission. In cases where an underlying pathology cannot be
identified, the patient is diagnosed with an idiopathic DCM. Current hypotheses regarding
causes of idiopathic DCM focus on chronic viral myocarditis and/or on autoimmune abnormalities.
Viral myocarditis may progress to an autoimmune phase and then to progressive cardiac
dilatation. Antibodies to the beta1-adrenergic receptor (beta1AR), which are detected
in a substantial number of patients with idiopathic DCM, may increase the concentration
of intracellular cAMP and intracellular Ca2 , a condition often leading to a transient
hyper-performance of the heart followed by depressed heart function and heart failure.;