SCINTIGRAPHIC EVIDENCE FOR CARDIAC SYMPATHETIC DYSINNERVATION IN LONG-TERM IDDM PATIENTS WITH AND WITHOUT ECG-BASED AUTONOMIC NEUROPATHY

To analyse the presence and extent of global and regional distribution s of cardiac sympathetic dysinnervation in long-term insulin-dependent diabetes mellitus (IDDM) without myocardial perfusion abnormalities ( Tc-99m-methoxy isobutyl isonitrile study), I-123-metaiodobenzylguanidi ne (I-123-MIBG) scintigraphy was performed in two clinically-comparabl e groups (20 diabetic patients with and 22 diabetic patients without E GG-based cardiac autonomic neuropathy). For comparison nine control su bjects without heart disease were investigated. Only six diabetic pati ents (27 %) without and one diabetic patient (5 %) with EGG-based auto nomic neuropathy were found to have a uniform homogeneous uptake of I- 123-MIBG, in contrast to a uniform homogeneous uptake in all control s ubjects. The uptake of I-123-MIBG in the posterior myocardium of diabe tic patients was smaller than in the anterior, lateral and septal myoc ardium (p < 0.001, p < 0.001, p = 0.001). In addition, diabetic patien ts with cardiac autonomic neuropathy (greater than or equal to two of five age-related cardiac reflex tests abnormal) demonstrated a more re duced uptake in the global, lateral and posterior myocardium than diab etic patients without (p < 0.01, p < 0.01, p < 0.001). A correlation b etween global or regional myocardial I-123-MIBG uptake, however, and d uration of diabetes, HbA(1c), body mass index or QT interval length wa s not observed. Our study demonstrates that cardiac sympathetic dysinn ervation is common in long-term IDDM even in patients without ECG-base d cardiac autonomic neuropathy and that the posterior myocardium is pr edominantly affected. We conclude that I-123-MIBG scintigraphy is a pr omising approach to further elucidate the pattern and natural history of myocardial dysinnervation in IDDM.