Use of iodine-123 metaiodobenzylguanidine scintigraphy to assess cardiac sympathetic denervation and the impact of hypertension in patients with non-insulin-dependent diabetes mellitus

The objectives of this clinical study using iodine-123 metaiodobenzylguanid ine (MIBG) scintigraphy were (a) to evaluate cardiac sympathetic denervatio n in non-insulin-dependent diabetes mellitus (NIDDM) patients with and with out hypertension and (b) to investigate the relation between cardiac sympat hetic denervation and prognosis in NIDDM patients. We compared clinical cha racteristics and MIBG data [heart to mediastinum (H/M) ratio and % washout rate (WR)] in a control group and NIDDM patients with and without hypertens ion. MIBG scintigraphy was performed in 11 controls and 82 NIDDM patients w ithout overt cardiovascular disease except for hypertension (systolic blood pressure greater than or equal to 140 and/or diastolic blood pressure grea ter than or equal to 90 mmHg). After MIBG examination, blood pressure was m easured regularly in all NIDDM patients. There were significant differences between 65 normotensive and 17 hypertensive NIDDM patients with respect to age (55+/-11 vs 63+/-12 years, respectively, P<0.05), prevalence of diabet ic retinopathy (12% vs 35%, respectively, P<0.05) and systolic blood pressu re (120+/-12 vs 145+/-16 mmHg, respectively, P<0.001). The H/M ratio in hyp ertensive NIDDM patients was significantly lower than in the control group (1.81+/-0.29 vs 2.27+/-0.20, respectively, P<0.01). During the follow-up pe riod (18+/- 12 months), 17 NIDDM patients newly developed hypertension afte r MIBG examination. There were no significant differences in their clinical characteristics compared with persistently normotensive or hypertensive NI DDM patients. %WR in patients with new onset hypertension was significantly higher than in the control group (30.88%+/-16.87% vs 12.89%+/-11.94%, resp ectively, P<0.05). Moreover, in these patients %WR correlated with duration from the date of MIBG scintigraphy to the onset of hypertension (r =-0.512 , P<0.05). Five NIDDM patients died during the follow-up period (four newly hypertensive patients and one normotensive patient). There were significan t statistical differences between the control group and non-survivors in te rms of age (54+/-11 vs 73+/-11 years, respectively, P<0.01), H/M ratio (2.2 7+/- 0.20 vs 1.64+/-0.36, respectively, P<0.01) and %WR (12.89%+/-11.94% vs 42.52%+/-22.39%, respectively, P<0.01). In conclusion, cardiac sympathetic denervation using MIBG scintigraphy observed in hypertensive NIDDM patient s, and was more profound in non-survivors. MIBG scintigraphy proved useful for the evaluation of NIDDM patients with new onset hypertension, and it wa s found that NIDDM patients with abnormalities on MIBG scintigraphy needed to be observe carefully.