AGT and atrial fibrillation: Apelin significantly inhibited Ang II-induced atrial fibrosis (HE:1.45 ± 0.11 vs 6.12 ± 0.16, P < 0.001; Masson:1.49 ± 0.25 vs 8.15 ± 0.23, P < 0.001; Picrosirius Red:1.98 ± 0.64 vs 9.59 ± 0.56, P < 0.001, respectively) and decreased the vulnerability of AF (inducibility of AF: z = −4.40, P < 0.001; total AF duration: z = −4.349, P < 0.001).