A Comparative Assessment of Cardiovascular Autonomic Reflex Testing and Cardiac 123 I-Metaiodobenzylguanidine Imaging in Patients with Type 1 Diabetes Mellitus without Complications or Cardiovascular Risk Factors

To compare the cardiovascular autonomic reflex tests (CARTs) with cardiac sympathetic innervation imaging with I-metaiodobenzylguanidine (MIBG) in patients with type 1 diabetes mellitus (T1DM). Forty-nine patients (29 males, mean age 36 ± 10 years, mean T1DM duration 19 ± 6 years) without cardiovascular risk factors were prospectively enrolled. Participants were evaluated for autonomic dysfunction by assessing the mean circular resultant (MCR), Valsalva maneuver (Vals), postural index (PI), and orthostatic hypotension (OH). Within one month from the performance of these tests, patients underwent cardiac MIBG imaging and the ratio of the heart to upper mediastinum count density (H/M) at 4 hours postinjection was calculated (abnormal values, H/M