FACILITATING INFLUENCE OF PROCAINAMIDE ON CONVERSION OF ATRIAL-FLUTTER BY RAPID ATRIAL-PACING

In a prospective, double-blind, randomized, placebo-controlled study w e investigated the facilitating influence of intravenous procainamide on conversion of atrial Butter by rapid atrial pacing. Fifty consecuti ve patients with spontaneous sustained atrial Butter were 1:1 randomiz ed into two homogenous groups: group A received 10 mg.kg(-1) procainam ide intravenously, group B placebo. After infusion there was a signifi cant (P<0.01) lengthening of the Butter cycle with respect to baseline in group Al exceeding the Butter cycle length of the control group (P <0.05). The overall success rate of rapid atrial pacing in restoring s inus rhythm was significantly higher after pre-treatment with procaina mide compared to placebo (100% vs 76%; P<0.0 5): 20 patients of group A reverted immediately after pacing to sinus rhythm, the remaining fiv e after a brief episode of atrial fibrillation. In the placebo group, 16 patients showed a prompt conversion to sinus rhythm and three after transient atrial fibrillation. In the remaining six patients, due to sustained pacing-induced atrial fibrillation, direct current cardiover sion was necessary, After administration of procainamide a less aggres sive stimulation protocol with significantly (P<0.01) longer paced cyc les to interrupt atrial Butter was achievable. In conclusion, intraven ous procainamide augments the efficacy of atrial pacing to convert atr ial Butter to sinus rhythm.