Abstract 4137488: Mild elevation of [K ⁺ ] ₀ reduces atrial fibrillation burden and enhances the efficacy of flecainide to suppress the arrhythmia: an experimental study.

Background: It is desirable to improve rhythm control management of atrial fibrillation (AF). Extracellular potassium ([K + ] 0 ) may affect AF generation and anti-AF efficacy of the sodium channel blockers. Methods: AF burden (i.e., percentage of time spent in AF) was determined in Langendorff-perfused guinea pig hearts in the range of [K + ] 0 of 3-6 mM in the presence and absence of flecainide (1.0 µM). Spontaneous and single premature beat-induced AF were monitored for 30 min in the presence of acetylcholine (0.3 µM). Results: Spontaneous AF episodes were consistently recorded at 3 mM [K + ] 0 but not at 4-6 mM [K + ] 0 either with or without flecainide. AF burden was progressively reduced with elevation of [K + ] 0 and anti-AF efficacy of flecainide progressively increased at the higher [K + ] 0 (Figure). * p<0.05 vs. 3 mM [K + ] 0 with no flecainide; ** p<0.05 vs. 3 mM [K + ] 0 with flecainide; # - p<0.05 vs. respective no flecainide. n=5-6 per group. Conclusion: Our findings indicate that mild elevation of [K + ] 0 significantly reduces AF burden and enhances the efficacy of flecainide to decrease AF burden.