CCL2 and atrial fibrillation: An increased expression of various inflammatory cytokines and chemokines such as interleukin-1 and interleukin-6, tumor necrosis factor-alpha (TNF-α), or monocyte chemoattractant protein-1 (MCP-1) can be observed to have progression to chronic atrial fibrillation and recurrence of atrial fibrillation after cardioversion (Hu et al., 2015).