Rapid slowing of the atrial fibrillatory rate after administration of AZD7009 predicts conversion of atrial fibrillation.

Background: Effects on the atrial fibrillatory rate (AFR) were studied during infusion with the combined potassium and sodium channel blocker AZD7009.

Methods And Results: Patients with persistent atrial fibrillation (AF) were randomized to AZD7009 or placebo. Thirty-five patients converted to sinus rhythm (SR) and were matched to 35 non-converters. The mean AFR before conversion was 231 fibrillations per minute (fpm), having decreased by 41%; in non-converters, it was 296 fpm at the end of infusion, having decreased by 26%. The rate of decrease was greater in converters at 5 min, -88 vs. -66 fpm (p=0.02), and at 10 min, -133 vs. -111 fpm (p=0.048). The AFR-SD and the exponential decay decreased. A small left atrial area was the only baseline predictor of conversion to SR.

Conclusions: AZD7009 produced a significantly more rapid decrease of the AFR in converters than in non-converters, but the AFR at baseline was not predictive of conversion.