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The term cardiomyopathy describes a heterogeneous group of diseases that directly alter cardiac structure, impair myocardial function, or alter myocardial electrical properties. Discoveries in molecular genetics and the description of (ion) channelopathies as diseases have prompted new definitions and classification of cardiomyopathies.1 Primary cardiomyopathies are diseases that solely or predominantly involve the myocardium1; the most common disorders are listed in Table 55-1. Secondary cardiomyopathies include heart muscle diseases associated with specific systemic disorders. At present, no classification method perfectly distinguishes all forms of cardiomyopathy, and overlap exists between categories.2,3 Secondary cardiomyopathies often present with hemodynamic findings similar to those of the idiopathic dilated or restrictive forms of cardiomyopathy. The most common causes of secondary cardiomyopathies are listed in Table 55-2. As a group, the cardiomyopathies are the third most common form of cardiac disease encountered in the United States, following coronary (ischemic) heart disease and hypertensive heart disease. Hypertrophic cardiomyopathy is the second most common cause of sudden cardiac death in the adolescent population and the leading cause of sudden death in competitive athletes.4

TABLE 55-1The Primary Cardiomyopathies
TABLE 55-2Common Causes of Secondary Cardiomyopathies

An in-depth discussion of each of the primary and secondary cardiomyopathies is beyond the scope of this chapter, and one is unlikely to make a specific diagnosis in the ED. This chapter discusses selected cardiomyopathies (Table 55-3). The cardiomyopathies usually present with signs of systolic and diastolic ventricular dysfunction. The ED evaluation will generally guide the need for urgent treatment, admission, or referral for further diagnostic evaluation, based on the severity of symptoms.

TABLE 55-3Features of Selected Cardiomyopathies

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