Abnormal rhythms in patients without known cardiac disease after a first dose of fingolimod

Background: Fingolimod is used to reduce the rates of relapse and slow the progression of disability in relapsing-remitting multiple sclerosis (RRMS). In-office monitoring of patients for 6 h after the first dose of fingolimod is currently recommended due to rare cardiac rhythm disturbances. The objective of this paper is to describe our experience with continuous electrocardiographic monitoring of patients with RRMS starting on fingolimod. Methods: Since changes to the FDA recommendations for first dose observation, a total of 59 patients with RRMS began treatment with fingolimod. After the first dose, all patients were observed for 6 h with continuous electrocardiographic telemetry, vital signs were checked every hour, and 12 lead ECG performed before and after the 6-h period. Results: Three out of 59 (5%) patients developed arrhythmia that led to discontinuation of fingolimod. The first patient had a sinus bradycardia with idioventricular escape rhythm that lasted 45 s and two patients developed second-degree atrio-ventricular block Mobitz type I. None of the patients had a history of prior cardiacc disease or was taking other medications that may cause arrhythmia or bradycardia. Conclusion: Continuous on-line electrocardiographic telemetry may detect abnormal rhythms in a small number of patients started on fingolimod. The clinical significance of these is unclear and warrants further study.