The term cardiomyopathy is used to describe
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 resulted in new definitions and classification
of cardiomyopathies.1 Some primary cardiomyopathies are
listed in Table 59-1. Secondary
cardiomyopathies include heart muscle diseases associated
with specific systemic disorders. They often present with hemodynamic
findings similar to those of the idiopathic dilated or restrictive
forms of cardiomyopathy. Some causes of secondary cardiomyopathies
are listed in Table 59-2. As a group, the
cardiomyopathies are the third most common form of cardiac disease
encountered in the U.S., following coronary (ischemic) heart disease
and hypertensive heart disease. Hypertrophic cardiomyopathy
(HCM) is the second most common cause of sudden cardiac death in
the adolescent population and the leading cause of sudden death
in competitive athletes.2
59-1 The Primary Cardiomyopathies |Favorite Table|Download (.pdf)
59-1 The Primary Cardiomyopathies
|Arrhythmogenic right ventricular cardiomyopathy/dysplasia|
|Left ventricular noncompaction|
|Conduction system disease|
|Catecholaminergic polymorphic ventricular tachycardia|
|Idiopathic ventricular fibrillation|
Mixed (genetic and nongenetic)
|Primary restrictive nonhypertrophied cardiomyopathy|
|Myocarditis (inflammatory cardiomyopathy)|
|Stress (“Takotsubo”) cardiomyopathy|
59-2 Common Causes of Secondary Cardiomyopathies |Favorite Table|Download (.pdf)
59-2 Common Causes of Secondary Cardiomyopathies
|Chemotherapeutic agents (doxorubicin)|
|Antiretroviral agents (zidovudine, didanosine)|
|Systemic lupus erythematosus|
|Nutritional deficiency (thiamine, selenium)|
|Endocrine (diabetes mellitus, hypothyroidism,
|Electrolytic disturbance (hypophosphatemia,
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 59-3). 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.
59-3 Features of Selected Cardiomyopathies |Favorite Table|Download (.pdf)
59-3 Features of Selected Cardiomyopathies
|Systolic and diastolic dysfunction||Dilated cardiomyopathy||Congestive heart failure||LVH|
|Chest pain||Poor R wave progression|
|Myocarditis||Fever||Nonspecific ST-T wave changes, often with
|Diastolic dysfunction||Hypertrophic cardiomyopathy||Dyspnea on exertion||LVH|
|Chest pain||Large septal Q waves|
|Prominent J wave|
|Systolic ejection murmur, increases with Valsalva and decreases
|Restrictive cardiomyopathies||“Square root sign” of left ventricular
filling pressures; easily confused with constrictive pericarditis||In some, low voltage of QRS; conduction disturbances; atrial fibrillation|
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