Reversal effect of Zhigancao decoction on myocardial fibrosis in a rapid pacing-induced atrial fibrillation model in New Zealand rabbits

OBJECTIVE: To evaluate the effect of Zhigancao decoction on reversal of right atrial myocardial fibrosis after rapid atrial pacing (RAP)-induced atrial fibrillation (AF). METHODS: New Zealand white rabbits were randomly divided into four groups: sham operation group (Group A: implanted electrodes, no RAP), pacing group (Group B: RAP-induced AF), Zhigancao soup water decoction Yin group (Group C: RAP-induced AF followed by Zhigancao soup Yin prescription twice a day for 30 days), and Zhigancao soup group (Group D: RAP-induced AF followed by Zhigancao water decoction twice a day for 30 days). The atrial myocardium was then examined for myocardial fibrosis by Masson staining, and protein expression of matrix metalloproteinase-9 (MMP-9) was immunohistochemically assessed. The right atrial appendage tissue field action potential duration (fAPD) was measured by microelectrode arrays. RESULTS: RAP successfully induced AF. Myocardial fibrosis was more severe in Groups B and C and less severe in Group D. Protein expression of MMP-9 was strongly positive in Groups B and C and weakly positive in Group D. The fAPD was significantly decreased in Groups B and C, but the decrease in Group D was not significant. CONCLUSION: Zhigancao decoction can reverse AF-induced myocardial fibrosis in rabbits and shorten the fAPD.