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Comparison in the same patient of aberrant conduction and bundle branch reentry after dofetilide, a new selective
H J Crijns1, J H Kingma, A T Gosselink
1Department of Cardiology, University Hospital Groningen, The Netherlands.
Insights
Dofetilide can cause abnormal heart rhythms by affecting intraventricular conduction. This study reveals a mechanism involving bundle branch reentrant beats, highlighting a potential proarrhythmic risk with this drug.
Area of Science:
- Electrophysiology
- Cardiac Arrhythmias
- Pharmacology
Background:
- Dofetilide, a Class III antiarrhythmic agent, is used for atrial fibrillation.
- Aberrant intraventricular conduction is a known potential side effect of Class III drugs.
- Understanding the mechanisms of drug-induced arrhythmias is crucial for patient safety.
Observation:
- This case study examined intraventricular conduction in an atrial fibrillation patient before and after dofetilide administration using endocardial recordings.
- Dofetilide induced aberrant conduction during atrial fibrillation.
- Aberrant conduction was reproducible with programmed atrial stimulation in sinus rhythm.
Findings:
- Dofetilide provoked aberrant intraventricular conduction.
- Bundle branch reentrant beats were observed during right ventricular stimulation.
- This phenomenon was linked to critical retrograde conduction delays and differences in refractoriness between the right bundle branch and right ventricular myocardium.
Implications:
- The findings suggest a specific proarrhythmic mechanism for dofetilide.
- This mechanism involves bundle branch reentry, potentially exacerbated by drug-induced refractoriness changes.
- Further investigation is warranted for dofetilide and similar Class III agents to mitigate proarrhythmic risks.
Abstract:
Dofetilide may induce aberrant intraventricular conduction due to its Class III effect. This report describes an atrial fibrillation patient in whom intraventricular conduction was studied before and after dofetilide using multiple endocardial recordings. Dofetilide provoked aberrant conduction during atrial fibrillation, and aberrancy could be mimicked with programmed atrial stimulation after restoration of sinus rhythm. However, during right ventricular stimulation, isolated bundle branch reentrant beats were recorded after induction of critical retrograde conduction delays. This occurred in the setting of relatively large differences in refractoriness between the right bundle branch and the right ventricular myocardium. This favored distal retrograde bundle branch block during ventricular extrastimulation, in turn enhancing bundle branch reentry. This potential proarrhythmic mechanism deserves close attention in the further development of dofetilide and also of other new "pure" Class III agents.