The aim of the present study was to investigate various properties of complex fractionated atrial electrograms (CFAEs) in different models of atrial fibrillation.Methods
Fifteen dogs were divided into three groups (five dogs/group): group 1 (pacing-induced atrial fibrillation group), group 2 (100 mM Ach-induced atrial fibrillation group), group 3 (500 mM Ach-induced atrial fibrillation group). Five sites from the left atrium in each dog were used as recording sites. Electric stimulations were used to induce atrial fibrillation. Effective refractory period (ERP) of each recording site and atrial fibrillation inducibility index were obtained at baseline and following sustained atrial tachypacing for 4 h (group 1) or acetylcholine (Ach) application (groups 2 and 3). During the first induced atrial fibrillation, recording sites with CFAEs were identified and domain frequency of CFAE was obtained.Results
ERPs decreased significantly compared to baseline in all groups (P < 0.001). There was no significant difference in decrements of ERPs at each site after pacing in group 1 (P = 0.646); in groups 2 and 3, significant differences were found in decrements of ERPs following Ach application when each site was compared (P < 0.05). Atrial fibrillation inducibility index increased in all groups compared to baseline (P < 0.05). During the first induced atrial fibrillation, CFAEs were recorded at all sites. There was no significant difference of domain frequencies in group 1 when each site was compared (P = 0.509), but significant differences in domain frequencies were found in groups 2 and 3 when each site was compared (P < 0.05).Conclusion
We identified that various characteristics of CFAEs may exist in different experimental models of atrial fibrillation. This may indicate different mechanisms of CFAEs.