Andersons pediatric cardiology 1644

Abstract Pediatric cardiomyopathies are rare diseases of heart muscle Although they may occur secondary to other disorders or anomalies, improved understanding of the genetics of cardiomyopathies has underscored the importance of mutations in these conditions Five major types of cardiomyopathy are described—hypertrophic, dilated, restrictive, arrhythmogenic right ventricular, and noncompaction cardiomyopathy— although there are circumstances where mixed phenotypes exist The distinctions also vary somewhat between the classification schemes of the European Society of Cardiology and American Heart Association Keywords Hypertrophic cardiomyopathy; dilated cardiomyopathy; restrictive cardiomyopathy; arrhythmogenic right ventricular cardiomyopathy; left ventricular noncompaction cardiomyopathy History of Classification of the Cardiomyopathies Cardiomyopathies are a heterogeneous group of diseases of the myocardium (Box 61.1) They were initially described as “heart muscle disease of unknown cause” by the World Health Organization/International Society and Federation of Cardiology (WHO/ISFC) classification in 1980.1 This categorized cardiomyopathy into dilated (DCM), hypertrophic (HCM), and restrictive (RCM) types as well as “unclassified cardiomyopathy” based on the morphologic characteristics of disease The WHO/ISFC added arrhythmogenic right ventricular cardiomyopathy (ARVC) to the initial three categories in 1995 while also acknowledging the goal of classifying cardiomyopathy not just by morphologic characteristics but also “if possible, by etiological/pathogenetic factors.”2 Subsequently the American Heart Association (AHA) definitions and classification of cardiomyopathies divided cardiomyopathies into two groups based on primary organ involvement (i.e., primary cardiac disease vs secondary cardiac manifestations of systemic disease).3 This system also attempted to incorporate the evolving understanding of the molecular genetics of cardiomyopathy, where possible, in addition to adding left ventricular noncompaction (LVNC) and channelopathies to the classification system The European Society of Cardiology (ESC) insisted that a classification system based on morphologic and functional phenotypes remained more clinically useful; thus it generally adheres to the previous classification scheme (including DCM, HCM, RCM, ARVC, and unclassified cardiomyopathies) with the addition of a subclassification for familial and nonfamilial forms.4 More recently, the MOGE(S) classification system has attempted to collate the various methods to classify the morphologic and clinical attributes of cardiomyopathies into a coherent system This nosology includes the morphofunctional phenotype (M), organ involvement (O), genetic or familial inheritance pattern (G), and etiologic annotation (E), including genetic defect or underlying disease/substrate The functional status (S) of the disease using both the American College of Cardiology/American Heart Association (ACC/AHA) heart failure (HF) stages and New York Heart Association (NYHA) functional class may also be added.5 This review attempts to incorporate both the AHA and ESC classification schemes, as these currently remain the most frequently used systems Box 61.1 Classification of Primary Cardiomyopathies HCM Sarcomeric protein mutations ■ β-Myosin heavy chain ■ Myosin binding protein C ■ Cardiac troponin I ■ Cardiac troponin T ■ α-Tropomyosin ■ Essential myosin light chain ■ Regulatory myosin light chain ■ Cardiac α-actin ■ Glycogen storage disease (GSD) ■ GSD II (Pompe disease) ■ GSD III (Forbes disease) ■ AMP kinase ■ LAMP2 (Danon disease) ■ Lysosomal storage diseases ■ α-Gal A (Anderson-Fabry disease) ■ MPS I (Hurler syndrome) ■ MPS II (Hunter syndrome) Disorders of fatty acid metabolism ■ Carnitine deficiency ■ Phosphorylase B-kinase deficiency ■ Mitochondrial cytopathies (e.g., MELAS, MERFF, LHON) Syndromic HCM ■ RASopathies (e.g., Noonan syndrome, LEOPARD syndrome) ■ Frataxin (Friedreich ataxia) ■ Beckwith-Wiedemann syndrome ■ Swyer syndrome ■ Other ■ Familial amyloid (e.g., transthyretin) ... They were initially described as “heart muscle disease of unknown cause” by the World Health Organization/International Society and Federation of Cardiology (WHO/ISFC) classification in 1980.1 This categorized cardiomyopathy into dilated (DCM), hypertrophic (HCM), and restrictive... cardiomyopathy, where possible, in addition to adding left ventricular noncompaction (LVNC) and channelopathies to the classification system The European Society of Cardiology (ESC) insisted that a classification system based on morphologic and functional phenotypes remained more clinically useful; thus... annotation (E), including genetic defect or underlying disease/substrate The functional status (S) of the disease using both the American College of Cardiology/ American Heart Association (ACC/AHA) heart failure (HF) stages and New York Heart Association (NYHA) functional class may also be added.5