Cardiac-specific knockdown of Bhlhe40 in mice by a type 9 recombinant adeno-associated virus (rAAV9)-shBhlhe40 significantly ameliorated Ang II-induced atrial dilatation, atrial fibrosis, and atrial inflammation, as well as the inducibility and duration of AF. The gene discussed is BHLHE40; the disease is atrial fibrillation.