Quinidine treatment of chronic lone atrial fibrillation.

Patients with chronic lone atrial fibrillation (LAF) were treated with quinidine according to a special schedule to establish sinus rhythm and prevent recurrences. Twenty-seven patients following this schedule were identified retrospectively. To prevent relapses, quinidine had been continued in 25 patients in doses 100 mg quid lower than those used for conversion. In 8 of the latter group, quinidine had to be discontinued or reduced. All patients converted to sinus rhythm. If well tolerated, quinidine prevented recurrence of LAF in 75% of those on long-term (mean follow-up 3.5 years) prophylaxis. After discontinuation of quinidine in 8 patients, LAF recurred in all but one patient. Side effects were observed in 22% of the patients and precluded continuation of the prophylaxis in 15%. No incidence of torsade de pointes was encountered.