Atrioventricular Block and Secondary Long QT Syndrome with Torsades de Pointes Storm Caused by Donepezil in Patient with Alzheimer’s Disease

Abstract

Donepezil is commonly used for Alzheimer’s dementia. It is a cholinesterase antagonist, therefore, expected to cause various arrhythmias through the increase of parasympathetic nerve tone. It is also expected to affect the cardiac repolarization phase and enhance QT interval. Although bradyarrhythmic episodes sometimes have been reported, tachyarrhythmias are rarely reported. We experienced 2 patients of syncopal episodes under taking donepezil. A 74 year-old male taking donepezi came to our hospital because of repeated syncopal episodes. ECG showed atrial fibrillation with slow ventricular response and QT prolongation (640 ms). He also presented repeated non sustained ventricular tachycardia. After discontinuation of donepezil, QT intervals recovered to 480 ms and there were no episodes of TdP. An 84 year-old female was admitted to our hospital because of repeated syncopal episodes. ECG on admission showed complete atrio-ventricular block. There also observed QT prolongation (800 ms) and incessant form of TdP needed repeated direct current shock. After discontinuation of donepezil, she recovered from QT prolongation. There were no episodes of TdP thereafter. In both patients permanent pacing therapy was performed in preparation for reappearance of arrhythmic episodes. Conclusion: We experienced rare 2 cases who presented both brady and tachyarrhythmic episodes simultaneously caused by cholinergic adverse effect of donepezil. Careful concern should be taken when using donepezil.