Challenge and Impact of Quinidine Access in Sudden Death Syndromes: A National Experience

Objectives: This study sought to determine the nature of quinidine use and accessibility in a national network of inherited arrhythmia clinics.

Background: Quinidine is an antiarrhythmic medication that has been shown to be beneficial in select patients with Brugada syndrome, early repolarization syndrome, and idiopathic ventricular fibrillation. Because of the low prevalence of these conditions and restricted access to quinidine through a single regulatory process, quinidine use is rare in Canada.

Methods: Subjects prescribed quinidine were identified through the Hearts in Rhythm Organization that connects the network of inherited arrhythmia clinics across Canada. Cases were retrospectively reviewed for patient characteristics, indications for quinidine use, rate of recurrent ventricular arrhythmia, and issues with quinidine accessibility.

Results: In a population of 36 million, 46 patients are currently prescribed quinidine (0.0000013%, age 48.1 ± 16.1 years, 25 are male). Brugada syndrome, early repolarization syndrome, and idiopathic ventricular fibrillation constituted a diagnosis in 13 subjects (28%), 6 (13%), and 21 (46%), respectively. Overall, 37 subjects (81%) had cardiac arrest as an index event. After initial presentation, subjects experienced 7.47 ± 12.3 implantable cardioverter-defibrillator shocks prior to quinidine use over 34.3 ± 45.9 months, versus 0.86 ± 1.69 implantable cardioverter-defibrillator shocks in 43.8 ± 41.8 months while on quinidine (risk ratio: 8.7, p < 0.001). Twenty-two patients access quinidine through routes external to Health Canada's Special Access Program.

Conclusions: Quinidine use is rare in Canada, but it is associated with a reduction in recurrent ventricular arrhythmias in patients with Brugada syndrome, early repolarization syndrome, and idiopathic ventricular fibrillation, with minimal toxicity necessitating discontinuation. Drug interruption is associated with frequent breakthrough events. Access to quinidine is important to deliver this potentially lifesaving therapy.