OBSCN and atrial fibrillation: Taken together, these changes in intracellular Ca2+ cycling align with the natural progression of AF, where 6-month Obscn-ΔIg58/59 atrial cardiomyocytes show elevated SR load, increased and prolonged Ca2+ release, and faster Ca2+ decay kinetics, while SR load and kinetics at 12 months are depressed or unchanged.