FMOD and atrial fibrillation: We found that fibrotic features, including the extracellular matrix, collagen, and collagen fibers, were notably enriched in atrial tissues from the SHR‐AF group than in those from the SHR group, whereas downregulation of FMOD expression decreased the extracellular matrix, collagen, and collagen fibers in atrial tissues from SHR‐AF.