Effects of Ivabradine on Cardiac Electrophysiology in Dogs with Age-Related Atrial Fibrillation

Background: Ivabradine is an inhibitor of mixed Na+-K+ current that could combine with HCN channels to reduce the trans-membrane velocity of funny current (If), heart rate, and cardiac efficiency, and thus be used for the treatment of cardiovascular diseases such as chronic heart failure. As an ion channel blocker, Ivabradine is also a poten-tial antiarrhythmic agent. Material/Methods: Twelve aging dogs (8–10 years old) underwent rapid atrial pacing for 2 months to induce age-related AF in this study. The dogs were randomly divided into the Ivabradine group and aging-AF group. The effects of Ivabradine on the electrophysiological parameters, including the effective refractory period (ERP) of the pulmonary veins and atrium, duration of AF, and inducing rate of AF, were investigated. Results: As compared to the aging-AF group, the ERPs of the left superior pulmonary vein (139.00±4.18 ms vs. 129.00±4.08 ms, P=0.005) and left auricle (135.00±3.53 ms vs. 122.00±4.47 ms, P=0.001) were significantly increased, while the duration of AF (46.60±5.07 s vs. 205.40±1.14 s, P=0.001) and inducing rate of AF (25 % vs. 60%, P=0.001) were significantly decreased. Conclusions: Ivabradine could effectively reduce the inducing rate of AF, and thus be used as an upstream drug for the pre