Impact of Diabetes on Cardiac Sympathetic Innervation in Patients With Heart Failure: A (123)I meta-iodobenzylguanidine ((123)I MIBG) scintigraphic study

OBJECTIVE: Impaired parasympathetic and sympathetic nervous system activity have been demonstrated in patients with diabetes mellitus (DM) and correlated with worse prognosis. Few data are available on the effect of DM on cardiac neuropathy in heart failure (HF). The aim of the current study was to assess cardiac sympathetic activity in HF patients with and without DM. RESEARCH DESIGN AND METHODS: Patients with severe HF (n = 75), with (n = 37) and without DM (n = 38), and 14 diabetic patients with normal cardiac function underwent (123)I meta-iodobenzylguanidine scintigraphy from which early and late heart-to-mediastinum (H/M) ratios were calculated. Clinical, echocardiographic, and biochemical data were measured. RESULTS: DM compared with non-DM patients showed significantly lower early (1.65 ± 0.21 vs. 1.75 ± 0.21; P < 0.05) and late H/M ratios (1.46 ± 0.22 vs. 1.58 ± 0.24; P < 0.03). Early and late H/M were significantly higher in DM patients without HF (2.22 ± 0.35 and 1.99 ± 0.24, respectively) than HF patients with (P < 0.0001) and without (P < 0.0001) DM. In HF patients, an inverse correlation between early or late H/M ratio and hemoglobin A(1c) (HbA(1c)) (Pearson = −0.473, P = 0.001; Pearson = −0.382, P = 0.001, respectively) was observed. In DM, in multivariate analysis, HbA(1c) and ejection fraction remained significant predictors of early H/M; HbA(1c) remained the only significant predictor of late H/M. No correlation between early or late H/M and HbA(1c) was found in non-DM patients. CONCLUSIONS: Diabetic patients with HF show lower cardiac sympathetic activity than HF patients not having DM or than DM patients with a similar degree of autonomic dysfunction not having HF. HbA(1c) correlated with the degree of reduction in cardiac sympathetic activity.