Controlled trial of a long-acting quinidine for maintenance of sinus rhythm after conversion of sustained atrial fibrillation

The prophylactic efficacy of quinidine arabogalactane-sulfate (QAGS), a long-acting derivative of quinidine was compared to no treatment in a randomized controlled trial in patients with DC converted sustained atrial fibrillation. Three months after countershock, 26 out of 103 treated patients and 46 out of 104 untreated patients were no longer in sinus rhythm (P<0.01). Baseline and follow-up characteristics of the two groups were well balanced apart from the use of cardiac glycosides. There were more cardiac glycoside users in the control group but the relapse rate was unrelated to this treatment. Patients of the QAGS group still in sinus rhythm at three months and who were good compliers, were randomly allocated to continue or stop QAGS. In this subset, the failure rate, one year after countershock was still lower in long-term QAGS treated patients.