EGR1 and atrial fibrillation: To test whether the effects of NAB1‐356 on atrial fibrosis, cytokine synthesis, and AF were mediated through EGR1, Gadd45b, and Runx1, we induced fibrosis and AF in circNAB1‐transgenic mice through TAC surgery, followed by delivery of EGR1, Gadd45b, and Runx1 expression plasmids with nanoparticles.