Colchicine initiated before radiofrequency-induced injury attenuates left atrial inflammation, fibrosis, and susceptibility for atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is the most frequently diagnosed cardiac arrhythmia. Catheter ablation using radiofrequency cauterization (CA-RFC) performed in the left atrium (LA) aims to isolate electrical sources of AF. This intervention is accompanied by frequent AF recurrences affecting 10% of patients at 30 days and 50% at one-year post-procedure. It has been suggested that inflammation could contribute to AF-recurrence post-CA-RFC. Given its anti-inflammatory and cardioprotective properties, colchicine has been proposed as a potential treatment to prevent AF recurrence post-CA-RFC. HYPOTHESIS: RFC can lead to atrial fibrosis, inflammation, and new onset AF, which may be mitigated by colchicine. METHODS: Male and female Wistar rats (225-275g) were divided into four groups: Sham or RFC, with or without colchicine (0.25 mg/kg/8h, intraperitoneally) starting 8 hours before surgery until D1 post-procedure. Sham animals underwent surgery without RFC. Electrophysiology and echocardiography assessments were performed on days 1 (D1) and 3 (D3) post-RFC. RESULTS: Colchicine significantly lowered RFC-induced AF vulnerability, improved LA conduction velocity, reduced LA fibrosis, and attenuated LA inflammation post-procedure. Colchicine also prevented RFC-induced CD11c+ macrophages while promoting CD206+ recruitment in the LA. CONCLUSION: Colchicine started before RFC may be an innovative strategy to prevent the development of LA arrhythmogenic substrate post-procedure.