Attention has been paid to the recognition of patients at risk of sudden cardiac death. Whereas the long-term prognosis of healthy subjects with frequent and complex ventricular premature complexes is similar to that of the normal population, coronary patients with frequent and complex ectopy are at high risk of sudden cardiac death; in this group, recent myocardial infarction and impaired left ventricular function increase the likelihood for sudden death. In a similar way, patients with idiopathic dilated cardiomyopathy and reduced left ventricular function, in whom frequent episodes of ventricular tachycardias or ventricular pairs are detected, are at high risk of sudden death. These patient groups with left ventricular impairment may potentially be treated with the alpha 1-antagonist indoramin, which has exhibited antiarrhythmic properties in animal experiments. In a therapeutic dose, indoramin prohibited reflex tachycardia but did not show any additional electrophysiologic effects. Therefore, no adverse effects on sinus node function or on atrioventricular conduction, or intraventricular conduction must be expected during therapy with indoramin.