Decreased connexin 43 and increased fibrosis in atrial regions susceptible to complex fractionated atrial electrograms

Abstract

Background and objectives: Complex fractionated atrial electrograms (CFAE) is distributed at preferential sites of atrium, and the mechanism underlying CFAE is not fully understood. We hypothesized that preexisting atrial abnormalities may be involved in the formation of CFAE.

Methods: Twelve pigs were subjected to acetylcholine infusion and right atrial pacing to induce sustained atrial fibrillation. The shortest complex interval map was used to visualize CFAE on three-dimensional anatomic structure of left atrium, and the CFAE sites were labeled by ablation. The expression of connexin 43 (Cx43) and myocardial fibrosis were examined.

Results: The expression of Cx43 at CFAE sites was significantly decreased when compared with non-CFAE sites, while myocardial fibrosis was enhanced in CFAE sites compared with non-CFAE sites.

Conclusions: These results suggested that the decreased expression of Cx43 and enhanced myocardial fibrosis at CFAE sites of the left atrium may be the structure abnormalities underlying CFAE.