CDK4 and atrial fibrillation: Various pharmacologic cancer treatments have been implicated in the development of AF, such as anthracyclines, tyrosine kinase inhibitors, alkylating agents, anti-metabolites, human epidermal growth factor receptor 2 (HER-2) antagonists, cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, BRAF/mitogen-activated extracellular signal-regulated kinase (MEK) inhibitors, immune checkpoint inhibitors, chimeric antigen receptor T-cell therapy (CAR-T) cell therapies and lenalidomide.