Dilated cardiomyopathy is a heart muscle disease of unknown aetiology'that is characterised by impaired systolic function of the left or both ventricles and is usually associated with cardiac enlargement. The diagnosis excludes heart muscle disease of known cause or associated with other disorders (systemic or pulmonary hypertension, coronary artery disease, valvar heart disease, or congenital cardiac abnormalities). Progressive deterioration because of symptoms of heart failure, low output state, and arrhythmia is common in dilated cardiomyopathy. The diagnosis of dilated cardiomyopathy is based on physical and non-invasive examinations (echocardiography and possibly multiple gated angiography) and cardiac catheterisation. Investigations include ventriculography, coronary angiography (to exclude ischaemic heart disease) and endomyocardial biopsy (to exclude active myocarditis or specific heart muscle disease). The main criteria for diagnosis are depressed ejection fraction (< 45-55%) 23 and ventricular dilatation (left ventricular internal diastolic dimensions> 2-7 cm/M2 of body surface area). Earlier stages of the disease may be characterised by cardiac dilatation without detectable dysfunc-tion in the resting state. In 5-31% of patients, however, cadiomegaly may be miimal or absent (mildly dilated cardiomyopathy). 45 Mortality seems to be correlated with the degree of systolic dysfunction, whereas dilatation is not an independent predictor of prognosis. 5