Cardiomyopathies are defined by structural and functional abnormalities of the ventricular myocardium that are unexplained by flow-limiting coronary artery disease or abnormal loading conditions. Historically, this group of disorders has been subdivided into primary disease, in which the heart is the only involved organ, and secondary forms where the cardiomyopathy is a manifestation of a systemic disorder. These Guidelines adopt a classification system proposed in a recent ESC position statement, in which cardiomyopathies are defined by specific morphological and functional criteria and then grouped into familial/genetic and non-familial/non-genetic subtypes, irrespective of the presence of extra-cardiac disease.
Hypertrophic cardiomyopathy (HCM) is defined by the presence of increased left ventricular (LV) wall thickness that is not solely explained by abnormal loading conditions.
This definition applies to children and adults and makes no a priori assumptions about aetiology or myocardial pathology. While this approach broadens the scope of the Guidelines and makes some recommendations more complex, it aligns with everyday clinical practice and is more likely to improve diagnostic accuracy and treatment.