RLN2 and atrial fibrillation: Currently, some researchers have recognized that the pleiotropic hormone relaxin-2 could be effective for AF management for several reasons: (1) its distinguished antiarrhythmic and cardioprotective properties, like its anti-inflammatory, anti-apoptotic, anti-fibrotic, anti-hypertrophic, and anti-oxidant effects; (2) its capability to inhibit Ang II; and 3) its effect regulating ECM turnover and decreasing collagen excessive deposition in cardiac tissues [41,42,43,111,112].