Europace Advance Access originally published online on January 18, 2008
Europace 2008 10(2):219-226; doi:10.1093/europace/eum286
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NONINVASIVE ELECTROPHYSIOLOGY
Cardiac repolarization during hypoglycaemia and hypoxaemia in healthy males: impact of renin–angiotensin system activity
1 Endocrinology Section, Division of Internal Medicine I, Nordsjællands Hospital - Hillerød, Helsevej 2, Hillerød DK-3400, Denmark; 2 Department of Neuroanaesthesia, Copenhagen University Hospital, Copenhagen, Denmark; 3 Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; 4 Department of Cardiology P, Gentofte University Hospital, Copenhagen, Denmark; 5 Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
Aims: Activity in the renin–angiotensin system (RAS) may influence the susceptibility to cardiac arrhythmia. To study the effect of basal RAS activity on cardiac repolarization during myocardial stress induced by hypoglycaemia or hypoxaemia in healthy humans.
Methods and results: Ten subjects with high RAS activity and 10 subjects with low RAS activity were studied on three different occasions: (i) hypoglycaemia (nadir P-glucose 2.7 ± 0.5 mmol/L), (ii) hypoxaemia (nadir pO2 5.8 ± 0.5 kPa), and (iii) normoglycaemic normoxia (control day). QT parameters were registered by Holter monitoring. Hypoglycaemia and hypoxaemia induced QTc prolongation (P < 0.001, both stimuli). The QT/RR slope and the VR increased as a function of hypoglycaemia, but were unaffected by hypoxaemia. Low RAS activity was associated with a steeper QT/RR slope in the recovery phase after both stimuli: hypoglycaemia: P = 0.04; hypoxia: P = 0.03. RAS activity had no impact on QTc [P = 0.48 (hypoglycaemia) and P = 0.40 (hypoxaemia)] or any of the other outcome variables.
Conclusion: Basal RAS activity has significant impact on QT dynamics, but not the corrected QT interval, during recovery from hypoglycaemia and hypoxaemia. The impact, however, is modest and more subtle than initially expected. The clinical relevance is unclear.
Key Words: Renin–angiotensin system, Cardiac repolarization, QT, Hypoglycaemia, Hypoxaemia, Substrate deficiency
* Corresponding author. Tel: +45 48296403; fax: +45 48294783. E-mail address: rsa{at}noh.regionh.dk
Manuscript submitted 12 October 2007. Accepted after revision 5 December 2007.
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