Journal
EUROPEAN JOURNAL OF HEART FAILURE
Volume 10, Issue 12, Pages 1172-1176Publisher
OXFORD UNIV PRESS
DOI: 10.1016/j.ejheart.2008.09.014
Keywords
Atrial fibrillation; Heart failure; Angiotensin; Remodelling
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Funding
- Sanofi-Aventis Deutschland GmbH
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Atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice. Indirect evidence from clinical trials demonstrates that chronic inhibition of the renin-angiotensin-system (RAS) significantly reduces the incidence of AF. Since mechanisms of this protective effect of RAS-blockade are poorly understood, we directly tested proarrhythmic effects of angiotensin II (Ang II) in human atrial myocardium. Methods: Isolated trabeculae from human atrial appendages (n = 80) were electrically stimulated. We assessed isometric force and incidence of arrhythmic extra contractions (AECs) with and without increasing concentrations of Ang II (1-1000 nmol/L) in the absence or presence of receptor-blockade by saralasin (non-specific ATR-antagonist), irbesartan (AT1R-antagonist) or PD123319 (AT2R-antagonist). Results: Twitch force and AECs concentration-dependently increased with Ang II. Effects became significant at concentrations > 1 nmol/L Ang II and were maximal at 1000 nmol/L (increase in twitch force to 157 +/- 14% and AECs from 0 to 80%) saralasin and irbesartan partially prevented the inotropic effect of 100 nmol/L Ang II (by 45 +/- 12% and 68 +/- 6%; p < 0.05), and completely prevented the occurrence of AECs. Conclusion: Ang II exerts direct pro-arrhythmic effects in human atrial myocardium. These effects are mediated by AT I-receptors and can be prevented by AT1R-blockade. This mechanism may contribute to the beneficial effects of RAS-blockade on AF in clinical trials. (C) 2008 Published by Elsevier B.V. on behalf of European Society of Cardiology.
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