The dilated cardiomyopathies: clinical aspects.

The dilated cardiomyopathies are characterized by an increase in left ventricular internal dimensions without an appropriate increase in ventricular wall thickness. The myocardial injury often goes unrecognized until the offending cause is no longer apparent. Although specific diagnoses and treatment can sometimes be established, the majority of cases are designated idiopathic but are believed to result from previous viral infections, autoimmune or genetic predisposition, or abnormalities of the coronary microvasculature. Despite impaired contractility and ventricular dilatation, compensated dysfunction may prevail for some time. Excessive fluid retention, neurohumoral activation, systemic vasoconstriction, and atrioventricular valve regurgitation promote progressive hemodynamic deterioration. The meticulous matching of diuretic and vasodilator therapy to specific hemodynamic goals, particularly the normalization of ventricular filling pressure, frequently allows restoration and maintenance of reasonable functional capacity even in patients with severe heart failure. Nevertheless, sudden death due to ventricular arrhythmias and occasionally to systemic emboli remains a major threat. Prophylactic use of antiarrhythmic agents and anticoagulant therapy is not of proven efficacy. Cardiac transplantation results in significant improvement in life expectancy for patients with dilated heart failure but is available only to a relatively small number of patients because of the limited donor supply. Accordingly, programs providing cardiac transplantation should be equally committed to providing optimal medical management that is the only option for the majority of patients with dilated cardiomyopathy.