TLR4 and atrial fibrillation: Protein levels of TLR4, MyD88, NLRP3, Cleavage‐Caspase‐1, Cleavage‐IL‐1β, TGF‐β1, p‐Smad2, collagen I, and collagen II were clearly higher in atrial tissues from the SHR‐AF group than in those from the SHR group.