Severe diabetic autonomic neuropathy was associated with a 33% increase in proximal left ventricular sympathetic innervation and a 33% decrease distally compared to DAN-free diabetics (P<0.01).
Cross-Sectional (n=39)
Does diabetes with varying severity of autonomic neuropathy alter regional left ventricular sympathetic innervation as measured by [11C]-HED PET?
Diabetes with severe autonomic neuropathy causes left ventricular sympathetic dysinnervation characterized by proximal hyperinnervation and distal denervation, potentially predisposing to electrical instability.
p-value: p=<0.01
BACKGROUND: Regional cardiac sympathetic hyperactivity predisposes to malignant arrhythmias in nondiabetic cardiac disease. Conversely, however, cardiac sympathetic denervation predicts increased morbidity and mortality in severe diabetic autonomic neuropathy (DAN). To unite these divergent observations, we propose that in diabetes regional cardiac denervation may elsewhere induce regional sympathetic hyperactivity, which may in turn act as a focus for chemical and electrical instability. Therefore, the aim of this study was to explore regional changes in sympathetic neuronal density and tone in diabetic patients with and without DAN. METHODS AND RESULTS: PET using the sympathetic neurotransmitter analogue 11C-labeled hydroxyephedrine (11C-HED) was used to characterize left ventricular sympathetic innervation in diabetic patients by assessing regional disturbances in myocardial tracer retention and washout. The subject groups comprised 10 diabetic subjects without DAN, 10 diabetic subjects with mild DAN, 9 diabetic subjects with severe DAN, and 10 healthy subjects. Abnormalities of cardiac 11C-HED retention were detected in 40% of DAN-free diabetic subjects. In subjects with mild neuropathy, tracer defects were observed only in the distal inferior wall of the left ventricle, whereas with more severe neuropathy, defects extended to involve the distal and proximal anterolateral and inferior walls. Absolute 11C-HED retention was found to be increased by 33% (P<0.01) in the proximal segments of the severe DAN subjects compared with the same regions in the DAN-free subjects (30%; P<0.01 greater than the proximal segments of the mild DAN subjects). Despite the increased tracer retention, no appreciable washout of tracer was observed in the proximal segments, consistent with normal regional tone but increased sympathetic innervation. Distally, 11C-HED retention was decreased in severe DAN by 33% (P<0.01) compared with the DAN-free diabetic subjects (21%; P<0.05 lower than the distal segments of the mild DAN subjects). CONCLUSIONS: Diabetes may result in left ventricular sympathetic dysinnervation with proximal hyperinnervation complicating distal denervation. This combination could result in potentially life-threatening myocardial electrical instability and explain the enhanced cardioprotection from beta-blockade in these subjects.
Stevens et al. (Tue,) conducted a cross-sectional in Diabetes and diabetic autonomic neuropathy (n=39). Diabetic autonomic neuropathy (DAN) vs. Diabetic subjects without DAN and healthy subjects was evaluated on Regional changes in sympathetic neuronal density and tone (absolute [11C]-HED retention) (p=<0.01). Severe diabetic autonomic neuropathy was associated with a 33% increase in proximal left ventricular sympathetic innervation and a 33% decrease distally compared to DAN-free diabetics (P<0.01).