NPPA and atrial fibrillation: In a study of 42 patients with chronic AF undergoing cardioversion, Wozakowska-Kaplon et al. [43] found that the average ANP concentration in AF patients was reduced by approximately two-fold within 24 h after successful cardioversion (to the same level as in the control group with sinus rhythm), whereas ANP levels remained the same in the group with unsuccessful cardioversion (Figure 5).