Europace Advance Access originally published online on June 4, 2008
Europace 2008 10(7):860-867; doi:10.1093/europace/eun137
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Repolarization
Cardiac repolarization during hypoglycaemia in type 1 diabetes: impact of basal renin–angiotensin system activity
1 Endocrinology Section, Department of Cardiology and Endocrinology, Hillerød Hospital, Helsevej 2, DK-3400 Hillerød, Denmark; 2 Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; 3 Department of Cardiology P, Gentofte University Hospital, Denmark; 4 Department of Neuroanaesthesia, Copenhagen University Hospital, Denmark; 5 Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
Aims: Hypoglycaemia-induced cardiac arrhythmias may be involved in the pathogenesis of the ‘dead-in-bed syndrome’ in patients with type 1 diabetes. Evidence suggests that the renin–angiotensin system (RAS) influences the occurrence of arrhythmias. The aim of this study was to explore if basal RAS activity affects cardiac repolarization during hypoglycaemia, thereby potentially carrying prognostic information on risk of the ‘dead-in-bed syndrome’.
Methods and results: Nine subjects with high RAS activity and nine subjects with low RAS activity were subjected to single-blinded placebo-controlled hypoglycaemia (nadir plasma glucose 2.4 mmol/L). QTc/QTcF and QT dynamics were registered by Holter monitoring. QTc prolonged during [8 (±2.3) ms, P < 0.01] and after [11 (±3) ms, P < 0.001] hypoglycaemia. Dynamic QT parameters reacted ambiguously. Low RAS activity was associated with a slightly more pronounced QT prolongation [6 (±3) ms, P = 0.04]. Adrenaline tended to increase more in the low-RAS group (P = 0.08) and was correlated to QTc (r = 0.67, P < 0.01) and QTcF (r = 0.58, P < 0.05) during hypoglycaemia.
Conclusion: Low basal RAS activity may be associated with a slightly more pronounced QT prolongation during hypoglycaemia, when compared with high RAS activity. The impact, however, is modest and the clinical consequence is unclear.
Key Words: Type 1 diabetes, Hypoglycaemia, ‘Dead-in-bed syndrome’, Cardiac repolarization, QT
* Corresponding author. Tel: +45 48296403; fax: +45 48294783. E-mail address: rsa{at}noh.regionh.dk
Manuscript submitted 24 February 2008. Accepted after revision 6 May 2008.