One potential link between AF, abnormal ventricular perfusion, and cardiomyocyte dysfunction is the occurrence of oxidative stress and the disruption of redox signaling through activation of the nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase; Kern et al., 2006; Camici and Crea, 2007; Doughan et al., 2008). Here, FMO5 is linked to atrial fibrillation.