NPPB and atrial fibrillation: Although the exact significance of decreased NT-proBNP levels in overweight or obese state of AF patients are not yet understood, it at least raises the possibility that there may be lesser natriuretic-mediated vasodilation and antagonism of the rennin-angiotensin system, or loss of natriuretic ability in overweight or obese patients, which may also play a role in the development of the AF in overweight or obese patients.