There are also data that the MRA spironolactone attenuates the deleterious effects of aldosterone in AF at the level of atrial tissue, where mineralocorticoid receptors appear to be up-regulated, lending support to the idea that an MRA may attenuate the risk for AF in heart failure patients with a −344CC genotype [20]. This evidence concerns the gene NR3C2 and atrial fibrillation.