Hypertrophic actions (Dschietzig et al., 2005). Atrial fibrillation, a common arrhythmia that develops during ageing-related fibrosis, hypertension, or heart failure, is suppressed by relaxin in spontaneously hypertensive rats, an established model of end-organ damage in response to hypertension (Parikh et al., 2013). The aforementioned effects of relaxin on atrial hypertrophy and fibrosis resulte