SMAD2 and atrial fibrillation: ↓ AF susceptibility and duration↓ left atrial diameter and area↓ MDA, NOX4↑ SOD activity↓ NLRP3, ASC, IL-1ß↓ caspase 1↓ p-CaMKII, p-RyR2↓ TGF-ß1, α-SMA, Col I, III, p-Smad2, p-Smad3