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

Abstract

Aim To compare the cardiovascular autonomic reflex tests (CARTs) with cardiac sympathetic innervation imaging with 123I-metaiodobenzylguanidine (MIBG) in patients with type 1 diabetes mellitus (T1DM). Patients and Methods 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 < 1.80). Results Twenty-nine patients (59%) had abnormal CARTs, and 37 (76%) patients had an H/M_4 < 1.80 (p = 0.456). MCR, PI, Vals, and OH were abnormal in 29 (59%), 8 (16%), 5 (10%), and 11 (22%) patients, respectively. When using H/M_4 < 1.80 as the reference standard, a cutoff point of ≥2 abnormal CARTs had a sensitivity of 100% but a specificity of only 33% for determining CAN. Conclusions CARTs are not closely associated with 123I-MIBG measurements, which can detect autonomic dysfunction more efficiently than the former. In comparison to semiquantitative cardiac MIBG assessment, the recommended threshold of ≥2 abnormal CARTs to define cardiovascular autonomic dysfunction is highly sensitive but of limited specificity and is independently determined by the duration of T1DM.

Efficacy and Safety of the Combination of Superoxide Dismutase, Alpha Lipoic Acid, Vitamin B12, and Carnitine for 12 Months in Patients with Diabetic Neuropathy

“…Age-specific reference values were applied. The first two CARTs address parasympathetic function, and Valsalva evaluates both parasympathetic and sympathetic function, whereas OH assesses sympathetic integrity [ 42 ].…”

Cardiovascular autonomic neuropathy in diabetes: Pathophysiology, clinical assessment and implications

“…A decrease in systolic blood pressure ≥ 20 mmHg and/or diastolic blood pressure ≥ 10 mmHg upon standing should be considered as an abnormal result. Moreover, several other symptoms or conditions can be identified with this test, such as weakness, faintness, dizziness, and visual impairment[ 4 , 62 , 63 ].…”

“…On the other hand, a potentially useful framework that overcomes these limitations is nuclear imaging, despite the high cost being a major limitation. It is a functional assessment tool used to evaluate presynaptic sympathetic nervous system function using myocardial scintigraphy[ 63 ].…”

Prevalence and Diagnosis of Diabetic Cardiovascular Autonomic Neuropathy in Beijing, China: A Retrospective Multicenter Clinical Study

“…On the other hand, measuring blood pressure changes during orthostatis, Valsalva (V) maneuvers and sustained isometric muscular strain aid in evaluating sympathetic function (Ewing et al, 1985). There is no specific algorithm for detecting CAN but, for proper diagnosis of the condition, it is recommended that more than one test is conducted to improve the sensitivity and reliability of the detection (Philips et al, 2011; Pop-Busui et al, 2017; Didangelos et al, 2018). The present study was undertaken with the aim of evaluating the prevalence of CAN among diabetic patients in Beijing, China.…”