Abstract Body (Do not enter title and authors here): 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.