High-dose cholinergic therapy with rivastigmine patch does not prolong QTc time in patients with Alzheimer's disease.

To the Editor: Cholinesterase inhibitors are widely accepted as established therapeutic intervention across the entire severity spectrum of Alzheimer’s disease. However, fear of increased corrected QT interval (QTc) time is one of the main reasons for nonprescription of cholinergic drugs.1 While it is generally accepted that therapeutic efficacy of cholinergic therapy is dose dependent, a large number of patients are treated with a low dose for fear of dose-dependent increase of QTc time. Previous studies in small numbers of patients reported that treatment with a low and medium dose of donepezil2 and rivastigmine3 did not prolong QTc time, while treatment with galantamine was shown to be associated with some risk of QTc time prolongation.4 Since these data were obtained, higher doses of donepezil and rivastigmine have been licensed to be used in routine clinical practice. Appraisal of risk of QTc time prolongation with a high dose of any cholinergic drug is thus of great clinical importance to reduce potential undertreatment of patients with Alzheimer’s disease. The objective of the current analysis was to determine whether high-dose rivastigmine patch induces prolongation of QTc time in patients with Alzheimer’s disease.