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Sequential bilateral bundle branch block during dofetilide, a new class III antiarrhythmic agent, in a patient with
H J Crijns1, J H Kingma, A T Gosselink
1Department of Cardiology, Thoraxcenter, University Hospital, Groningen, The Netherlands.
Introduction:
The mechanism of wide QRS complex tachycardias during dofetilide infusion was studied in a patient with atrial fibrillation.
Methods And Results:
Endocardial recordings from the intraventricular conduction system showed that dofetilide caused "classic" aberrant conduction (Ashman phenomenon, typical QRS morphology) at high prematurity ratios (preceding interval = 1.78 x coupling interval--290), thus mimicking ventricular ectopy. In addition, there was frequent sequential bilateral bundle branch block, caused by a significant difference in preceding bundle-to-bundle intervals (mean difference +/- 1 SD: 74 +/- 26 msec).
Conclusion:
The present findings may prove helpful in the clinical assessment of wide QRS complex rhythms after dofetilide and possibly other "pure" Class III antiarrhythmics.