CALCR and cardiac arrhythmia: Therefore, this study aimed to explore (i) the role of miR-31–5p as an upstream regulator of CTR signalling in remodelled atrial myocardium from patients with persAF, and (ii) the therapeutic potential of targeting the miR-31–5p/CTR mRNA interaction to prevent and/or reverse atrial fibrosis and arrhythmia.