Effect of cyclosporine-A on electrophysiological properties of atria in tachycardia-induced atrial fibrillation

Objective To investigate the effects of ciyclosporine-A (CsA), a calcineurin (CaN) inhibitor, on electrophysiological properties of atria in canine tachycardia-induced model of AF. Methods Eighteen healthy adult mongrel canines weighing 17.0 to 23.2 kg(ranged from 2 to 4 years old)were randomized to 3 groups, Sham group (no pacemaker was implanted), atrial tachypacing group (ATP group) and CsA group (atrial tachypacing plus oral administration of CsA 10 mg?kg-1?d-1). Electrophysiological tests were performed on each group at baseline and after 8 weeks’ tachypacing. Measurements included atrial effective refractory period(AERP), conduction velocity (CV), wave length (WL), atrial fibrillation load and rate-adaptability. Results After 8 weeks’ atrial tachypacing, ATP and CsA groups showed significant longer duration of the P wave, shorter AERP, decreased adaptation of AERP, slower CV, shorter WL and longer AF duration compared to the sham group (all P<0.05). AERP of the CsAgroup was longer than that of ATP group (P<0.05), but there were no differences in rate-adaptability, CV, incidence of induced AF and AF duration between CsA group and ATP group. Conclusions Our results suggest that calcineurin pathway intervention by CsA have a positive effect on tachycardia-induced electrical remodeling of atria, but can not prevent or reverse AF.