Europace Advance Access originally published online on November 5, 2008
Europace 2009 11(1):70-74; doi:10.1093/europace/eun302
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Atrial Fibrillation
Acute beta-adrenoceptor blockade improves efficacy of ibutilide in conversion of atrial fibrillation with a rapid ventricular rate
2nd Cardiology Department, General Hospital G. Papanikolaou, Exochi, Thessaloniki, Greece
Aims: Activation of beta-adrenoceptors attenuates prolongation of action potential duration induced by blockade of the delayed rectifier potassium current. We examined whether acute administration of beta-blocker could enhance ibutilide (IB) efficacy in conversion of atrial fibrillation (AF) with a rapid ventricular rate.
Methods and results: Ninety patients (aged 63 ± 13.5 years) with rapidly conducting AF were randomized in to two groups. Group A (n = 44) received esmolol titrated to achieve a heart rate of <100 bpm followed by IB co-administration, while Group B (n = 46) were treated with IB as monotherapy. In Group A, 29 patients (67%) converted to sinus rhythm (SR) compared with 21 (46%) in Group B (P = 0.04). The use of esmolol was the most important predictor for cardioversion (P = 0.009). The slower the heart rate at the time of IB initiation, the higher the likelihood for cardioversion (P = 0.015). Patients in Group A had significantly shorter corrected QT interval (QTc) at the time of conversion than those in Group B (433 vs. 501 ms, P = 0.003). Two patients in Group A developed severe bradycardia, whereas three patients in Group B developed severe ventricular tachycardia (VT).
Conclusion: Compared with IB monotherapy, the combination therapy of esmolol and IB appears to be more effective in conversion of rapidly conducting AF back to SR. The addition of beta-blocker reduces QTc prolongation and diminishes the risk of VT at the expense, however, of increased bradycardic events.
Key Words: Ibutilide, Esmolol, Cardioversion, Atrial fibrillation
* Corresponding author. Tel: +30 694 426 7643; fax: +30 231 330 7676. E-mail address: nfrag{at}vodafone.net.gr
Manuscript submitted 1 July 2008. Accepted after revision 13 October 2008.
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