Isotopes and idiopathic dilated cardiomyopathy.

Idiopathic dilated cardiomyopathy is a myocardial disease of unknown cause which carries a poor prognosis. Different isotopic techniques provide infor mation about the factors which influence its development and about its seve rity and potential to progress. The results of isotopic right and left vent riculography are important in establishing the prognosis. Thallium 201 myoc ardial scintigraphy can show myocardial perfusion defects which are often m ultiple and widespread. The prognostic significance of these abnormalities has not been fully established. Gallium-67 myocardial scintigraphy may show inflammatory phenomena within the myocardium, orientating the diagnosis to myocarditis. MIBG scintigraphy assesses adrenergic presynaptic activity wh ich, when decreased (heart/mediastinum uptake < 1.2), carries a very poor p rognosis. Finally, anti-myosin antibody myocardial scintigraphy may show re gions of acute or subacute cellular destruction which may be markers of myo cardial toxicity of alcohol and have important prognostic implications in t he medium term.