Introduction

Cardiomyopathies (CMPs) are “myocardial diseases characterized by structurally and functionally abnormal heart muscle and absence of other diseases sufficient to cause the observed myocardial abnormality”.1 They are currently classified according to their morphofunctional phenotype as hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy (RCM), dilated cardiomyopathy (DCM) and arrhythmogenic right ventricular cardiomyopathy (ARVC).1 ,2 Familial CMP is diagnosed when two or more members are affected. Sporadic CMP is diagnosed when a unique family member is affected, although it may represent the manifestation of a de novo genetic disease.3 DCM is characterised by “the presence of dilatation and systolic impairment of the left or both ventricles unexplained by abnormal loading conditions or coronary artery disease”.1 The estimated incidence and prevalence of DCM are 6.0 per 100 000 person-years and 1 in 2500, respectively, but these data are based on clinical criteria obtained in the genetic era.4 New estimates5 based on contemporary data that include early phenotypes, systematic family screening and genetic testing are likely to show that DCM is more common than previously appreciated.6–14

In this article, DCM is grouped into familial/genetic and non-familial/non-genetic subtypes, irrespective of the presence of extracardiac disease.1 DCM represents the end-phenotype of myocardial damage induced by different mechanisms, but specific causes can be identified using molecular and genetic assays, high-resolution and functional …