A Novel Method for the Assessment of Autonomic Neuropathy in Type 2 Diabetic Patients: a Comparative Evaluation of123I-MIBG Myocardial Scintigraphy and Power Spectral Analysis of Heart Rate Variability

The correlation between the degree of sympathetic denervation measured through 123I-MIBG Myocardial Scintigraphy and Power Spectral Analysis of consecutive R-R records was investigated in order to evaluate their potential application for the assessment of myocardial autonomic neuropathy in patients with diabetes mellitus. This study comprised 42 patients with Type 2 diabetes. Low frequency (0.02-0.09 Hz) components of the power spectral density were measured as markers of sympathetic activity. The myocardial uptake of 123I-MIBG was measured by using the single photon emission computed tomography (SPECT) and the early and delayed images were recorded. Scoring from 0 to 3 of the 123I-MIBG uptake of various cardiac segments (7) was performed and the total uptake was calculated. The washout rate in the whole myocardium was determined. The values obtained in the group with diabetic autonomic neuropathy (DAN) without orthostatic hypotension (OH) were significantly lower as compared to those of the (DAN (-)) group in the delayed images. The washout rate of the OH (-) group was also significantly higher than the DAN (-) group. There was significant difference between the images and the washout rate of OH (+) and OH (-) groups. There was a significant correlation between Power Spectral Analysis and SPECT (early, delayed images, and washout rate). Of these, the delayed image showed the strongest correlation (r = 0.55, p < 0.01). Further, the QTc interval showed a significant inverse correlation with the delayed image (r = -0.44, p < 0.05). In conclusion, these results suggest that the cardiac 123I-MIBG scintigraphy could be a useful method for the assessment of the myocardial autonomic neuropathy in patients with diabetes mellitus.