Figure 1.

Summary of mechanisms underlying the initiation and maintenance of atrial fibrillation. Atrial fibrillation can be maintained by either re-entry or sustained ectopic activity. Trigger (commonly from an ectopic beat) combined with vulnerable substrate facilitate the development of re-entry. Inflammation, ANS dysfunction, structural remodelling, ion channel, connexin dysfunction and Ca²⁺ handling abnormalities underline the generation and progression of vulnerable substrate. Risk factors (modifiable and non-modifiable) are the basal component closely associated with atrial fibrillation. OSA, obstructive sleep apnea; DM, diabetes mellitus; COPD, chronic obstructive pulmonary disease; ANS, autonomic nerve system; Cx, connexin; EAD, early afterdepolarization; DAD, delayed afterdepolarization (Online version in colour.).