CCL2 and atrial fibrillation: In addition to macrophage polarization, the levels of IL-1β, MCP-1, and TNF-α in atrial tissue increased in the AF canine model following prolonged rapid atrial pacing, while reduced macrophage polarization due to the administration of TRAM-34 significantly inhibited the induction of AF and reduced the levels of IL-1β, MCP-1, and TNF-α in the atrium.