HDAC9 and atrial fibrillation: Finally, the lack of Kcnn1 regulation by Hdacs1, 4 and 5 indicates specificity of HDAC‐KCNN1 interactions and argues against an unspecific class effect of HDACs. Differential regulation of KCNN1 expression by HDACs significantly extends our current knowledge on cardiac electrophysiology and ionic remodeling in AF.