Cardiac autonomic neuropathy in patients with diabetes and no symptoms of coronary artery disease: comparison of (123)I-metaiodobenzylguanidine myocardial scintigraphy and heart rate variability

PURPOSE: The purpose of this study was to evaluate the prevalence of cardiac autonomic neuropathy (CAN) in a cohort of patients with type 2 diabetes, truly asymptomatic for coronary artery disease (CAD), using heart rate variability (HRV) and (123)I-metaiodobenzylguanidine ((123)I-mIBG) myocardial scintigraphy. METHODS: The study group comprised 88 patients with type 2 diabetes prospectively recruited from an outpatient diabetes clinic. In all patients myocardial perfusion scintigraphy, CAN by HRV and (123)I-mIBG myocardial scintigraphy were performed. Two or more abnormal tests were defined as CAN-positive (ECG-based CAN) and one or fewer as CAN-negative. CAN assessed by (123)I-mIBG scintigraphy was defined as abnormal if the heart-to-mediastinum ratio was <1.8, the washout rate was >25%, or the total defect score was >13. RESULTS: The prevalence of CAN in patients asymptomatic for CAD with type 2 diabetes and normal myocardial perfusion assessed by HRV and (123)I-mIBG scintigraphy was respectively, 27% and 58%. Furthermore, in almost half of patients with normal HRV, (123)I-mIBG scintigraphy showed CAN. CONCLUSION: The current study revealed a high prevalence of CAN in patients with type 2 diabetes. Secondly, disagreement between HRV and (123)I-mIBG scintigraphy for the assessment of CAN was observed.