5.3 Etiology of dilated cardiomyopathy
Many disorders or conditions may lead to myocardial dysfunction and, subsequently, dilated cardiomyopathy. We are just beginning to understand the wide spectrum of possible etiologies (see Table below).
| Cause | |
|---|---|
| Infectious | viral, rickettsial, bacterial, fungal, metazoal, protozoal |
| Metabolic | endocrine diseases (i.e., hyperthyroidism, hypothyroidism, acromegaly, myxedema, hypoparathyroidism, hyperparathyroidism), diabetes mellitus, electrolyte imbalance (e.g., potassium, phosphate, magnesium) |
| Nutritional | thiamine deficiency (beriberi), protein deficiency, starvation, carnitine deficiency |
| Toxic | drugs, poisons, foods, anesthetic gases, heavy metals, ethanol |
| Infiltrative | hemochromatosis, amyloidosis, glycogen storage disease |
| Physical agents | extreme temperatures, ionizing radiation, electric shock, non-penetrating chest injury |
| Neuromuscular disorders | muscular dystrophy (limb-girdle [Erb's dystrophy], Duchenne dystrophy, fascioscapulohumeral [Landouzy-Dejerine dystrophy]), Friedreich's disease, myotonic dystrophy |
| Secondary to other cardiovascular disease | ischemia, hypertension, valvular disease, tachycardia induced |
| Immunologic | post-vaccination, serum sickness, transplant rejection |
| Other | genetic (i.e. non-compaction) Whipple’s disease, Lyme disease, collagen vascular disease, Granulomatous (sarcoidosis), primary cardiac tumor, senile, peripartum |
Echocardiography rarely reveals the true etiology of dilated cardiomyopathy. Excepted from this statement are specific genetic forms such as isolated non-compaction cardiomyopathy, in which a typical morphologic appearance is indicative (or at least suggestive) of the disease. More often, the clinician has to correlate echocardiographic findings with the existing clinical information. For example, pericardial effusion in combination with signs of infection suggests that perimyocarditis is the cause of dilated cardiomyopathy, especially when markers of myocardial damage (troponin, CPK) are also elevated. In many other situations, it is the patient’s history and the time when cardiomyopathy occurred that provide clues as to the cause of dilated cardiomyopathy (e.g. chemotherapy-induced cardiomyopathy, systemic disease).
The etiology of dilated cardiomyopathy remains ambiguous in many patients; the condition is then referred to as idiopathic cardiomyopathy. The frequency of idiopathic cardiomyopathy strongly depends on whether other diagnostic procedures and tests such as myocardial biopsy, immunohistochemistry, PCR analysis, or genetic analysis are performed.