AGT and vitamin D deficiency: In addition, an activated RAAS can lead to AF due to oxidative stress and inflammation.25 Vitamin D prevents AF by inhibiting RAAS activity.26 The other hypothesis for how AF develops in vitamin D deficiency is that tissue angiotensin II can contribute to changes in the atrial structure by inducing apoptosis of cardiomyocytes.27 Consequently angiotensin is inhibited and atrial structure is protected by vitamin D.