Background-Automatic implantable cardioverter-defibrillator therapy is considered the only effective treatment for high-risk patients with Brugada syndrome. Quinidine depresses I to current, which may play an important role in the arrhythmogenesis of this disease. Methods and Results-The effects of quinidine bisulfate (mean dose, 1483Ϯ240 mg) on the prevention of inducible and spontaneous ventricular fibrillation (VF) were prospectively evaluated in 25 patients (24 men, 1 woman; age, 19 to 80 years) with Brugada syndrome. There were 15 symptomatic patients (including 7 cardiac arrest survivors and 7 patients with unexplained syncope) and 10 asymptomatic patients. All 25 patients had inducible VF at baseline electrophysiological study. Quinidine prevented VF induction in 22 of the 25 patients (88%). After a follow-up period of 6 months to 22.2 years, all patients are alive. Nineteen patients were treated with quinidine for 6 to 219 months (meanϮSD, 56Ϯ67 months). None had an arrhythmic event, although 2 had non-arrhythmia-related syncope. Administration of quinidine was associated with a 36% incidence of side effects that resolved after drug discontinuation. Conclusions-Quinidine effectively prevents VF induction in patients with Brugada syndrome. Our data suggest that quinidine also suppresses spontaneous arrhythmias and could prove to be a safe alternative to automatic implantable cardioverter-defibrillator therapy for a substantial proportion of patients with Brugada syndrome. Randomized studies comparing these two therapies seem warranted.

Our results suggest that EP-guided therapy with Class IA agents is a reasonable, safe, and effective approach for the long-term management of patients with idiopathic VF. A randomized prospective study of EP-guided Class IA therapy in patients with ICDs seems warranted.

The long-term reproducibility of the EP efficacy of quinidine in patients with idiopathic VF and Brugada syndrome is excellent. EP-guided quinidine therapy represents a valuable long-term alternative to ICD therapy in these patients.