Donepezil, galantamine, and rivastigmine are the three acetylcholinesterase inhibitors (AChEIs), out of a total of only four medications prescribed in the treatment of Alzheimer's Disease (AD) and related dementias. These medications are known to be associated with bradycardia given their mechanism of action of increasing acetylcholine (ACh). However, in March 2015, donepezil was added to the CredibleMeds “known‐risk” category, a list where medications have a documented risk for acquired long‐QT syndrome (ALQTS) and torsades de pointes (TdP) – a malignant ventricular arrhythmia that is a different adverse event than bradycardia (and is not necessarily associated with ACh action). The purpose of this article is to review the three AChEIs, especially with regards to mechanistic differences that may explain why only donepezil poses this risk; several pharmacological mechanisms may explain why. However, from an empirical point‐of‐view, aside from some case‐reports, only a limited number of studies have generated relevant information regarding AChEIs' and electrocardiogram findings; none have specifically compared donepezil against galantamine or rivastigmine for malignant arrhythmias such as TdP. Currently, the choice of one of the three AChEIs for treatment of AD symptoms is primarily dependent upon clinician and patient preference. However, clinicians should be aware of the potential increased risk associated with donepezil. There is a need to examine the comparative risk of malignant arrhythmias among AChEIs users in real‐world practice; this may have important implications with regards to changes in AChEI prescribing patterns.

Certain medications are reported to be associated with acquired long‐QT syndrome (ALQTS), which can degenerate into a potentially severe ‘malignant’ arrhythmia known as torsades de pointes (TdP). However, population‐based estimations of the incidence of medication‐associated malignant arrhythmia are limited. The purpose of this article is to review the clinical symptoms, cellular mechanism, categorization, and risk factors of these malignant arrhythmias, as well as illustrate results and methodological limitations of epidemiological literature which have previously estimated population‐based incidence of ALQTS and malignant arrhythmia. Administrative databases in universal healthcare systems (such as Canada) can be used to provide a robust estimate of this incidence. We present a valid operational definition of medication‐associated malignant arrhythmia, using Canadian hospital administrative data linked to prescription databases that can be used to estimate the population‐based incidence. An estimation of incidence may have important implications with regard to understanding the potential widespread distribution of this adverse effect—which may influence medication prescribing patterns.