Classification of cardiomyopathies

For over 50 years, the definition and classification of cardiomyopathies have remained anchored in the concept of ventricular dysfunction and myocardial structural remodelling due to unknown cause. The concept of idiopathic was first challenged in 2006, when the American Heart Association classification subordinated the phenotype to the aetiology. Cardiomyopathies were classified as genetic, acquired, and mixed. In 2008, the European Society of Cardiology proposed a phenotype-driven classification that separated familial (genetic) from non-familial (non-genetic) forms of cardiomyopathy. Both classifications led the way to a precise phenotypic and aetiological description of the disease and moved away from the previously held notion of idiopathic disease. In 2013, the World Heart Federation introduced a descriptive and flexible nosology—the MOGE(S) classification—describing the morphofunctional (M) phenotype of cardiomyopathy, the involvement of additional organs (O), the familial/genetic (G) origin, and the precise description of the (a)etiology including genetic mutation, if applicable (E); reporting of functional status such as American College of Cardiology/American Heart Association stage and New York Heart Association classification (S) was left optional. MOGE(S) is a bridge between the past and the future. It allows description of comprehensive phenotypic data, all genetic and non-genetic causes of cardiomyopathy, and incorporates description of familial clustering in a genetic disease. MOGE(S) is the instrument of precision diagnosis for cardiomyopathies. The addition of the early and unaffected phenotypes to the (M) descriptor outlines the clinical profile of an early affected family member; the examples include non-dilated hypokinetic cardiomyopathy in dilated cardiomyopathy and septal thickness (13–14 mm) in hypertrophic cardiomyopathy classes.