Classification, Epidemiology, and Global Burden of Cardiomyopathies

Abstract

In the past 25 years, major advances were achieved in the nosography of cardiomyopathies, influencing the definition and taxonomy of this important chapter of cardiovascular disease. Nearly, 50% of patients dying suddenly in childhood or adolescence or undergoing cardiac transplantation are affected by cardiomyopathies. Novel cardiomyopathies have been discovered (arrhythmogenic, restrictive, and noncompacted) and added to update the World Health Organization classification. Myocarditis has also been named inflammatory cardiomyopathy. Extraordinary progress accomplished in molecular genetics of inherited cardiomyopathies allowed establishment of dilated cardiomyopathy as mostly cytoskeleton, force transmission disease; hypertrophic-restrictive cardiomyopathies as sarcomeric, force generation disease; and arrhythmogenic cardiomyopathy as desmosome, cell junction disease. Channelopathies (short and long QT, Brugada, and catecholaminergic polymorphic ventricular tachycardia syndromes) should also be considered cardiomyopathies because of electric myocyte dysfunction. Cardiomyopathies are easily diagnosed but treated only with palliative pharmacological or invasive therapy. Curative therapy, thanks to insights into the molecular pathogenesis, has to target the fundamental mechanisms involved in the onset and progression of these conditions.

Cardiomyopathies

“…In 1982, Marcus et al 49 described 24 patients with recurrent tachycardias, right ventricular dilatation, and failure. Ventricular postexcitation waves, described as small undulations in the ST segment, were observed in one third of the patients ( Figure 6 in the article by McKenna et al 11 ). Nava, Thiene, and their collaborators tied these strands together by recognizing that this disorder, initially referred to as arrhythmogenic right ventricular cardiomyopathy, was an important cause of death in patients <35 years.…”

“…In 2008, the European Heart Association did not accept this addition. 10 The diagrams illustrating the classifications developed by these 2 panels are shown in Figures 10 and 11 in the article by McKenna et al 11 This war of words was averted when the Heart Rhythm Society (an American society) and the European Heart Rhythm Association prepared a consensus statement on genetic testing of the channelopathies and cardiomyopathies. 12 Oncologists have developed a staging system for cancer that has been successfully used for many years.…”

“…27 In 1949, Evans reported that idiopathic ventricular hypertrophy may, in some instances, be familial. 28 In 1958, Donald Teare-a pathologist-studied the hearts of 9 patients with left ventricular hypertrophy, 8 of whom had died suddenly; he reported that the hypertrophy was asymmetrical and most severe in the ventricular septum 29 ( Figure 4 in the article by McKenna et al 11 ). Thus, by 1958, the condition now termed HCM had the following characteristics: asymmetrical left ventricular hypertrophy causing obstruction to ventricular outflow, a familial association in some patients and an increased risk of arrhythmias, and sudden cardiac death.…”

“…He named it amyloid, resembling the Latin word for starch, amylum. 54 In 1922, cardiac amyloidosis was described, 55 followed by the discovery of familial amyloid heart disease 56 ( Figure 14 in the article by McKenna et al 11 ). In 1948, the clinical and hemodynamic similarities between cardiac amyloidosis and chronic constrictive pericarditis were noted.…”

“…Left ventricular noncompaction ( Figure 9 in the article by McKenna et al 11 ) is frequently associated with DCM and with HCM in children. 86,87 Our understanding of this cardiomyopathy is still relatively primitive.…”