P4HA3 and atrial fibrillation: Herein, we characterized atrial fibrosis in cell and animal models, observed changes in the abilities of atrial fibroblast migration and proliferation, along with miR-205 and its target gene P4HA3, in atrial fibrosis caused by Ang II, and determined whether miR-205 overexpression attenuates atrial fibrosis and AF in models.