Sympathetic Denervation of Myocardium Demonstrated by 123 I-MIBG Scintigraphy in Pure Progressive Autonomic Failure

123I-MIBG myocardial scintigrams obtained in 2 cases with pure progressive autonomic failure are presented. In the less advanced case, 123I-MIBG myocardial SPECT disclosed uptake defects of radioisotopes in both the apical region and the inferior wall and a marked decrease in uptake in the lateral wall. However, residual radioactivity was demonstrated in the anterior wall. In the terminal stage, radioactivity over the whole heart was undetectable in planar images, so as to be of no use to obtain SPECT images. These scintigrams might suggest where the sympathetic denervation began and subsequently extended to the whole myocardium in the course of the disease. In addition, 123I-MIBG scintigraphy was recommended in a case with the disease, since an unequal impairment of myocardial sympathetic nervous system has been described to probably induce fatal arrhythmias which were the cause of sudden death in this case.