REN and atrial fibrillation: It has been shown that the activation of efferent sympathetic renal nerve fibres results in: (i) renin release via β1 adrenoreceptor activation in the juxtaglomerular cells, with downstream activation of the renin–angiotensin–aldosterone system, (ii) increase in renal tubular sodium reabsorption via α adrenoceptors, and (iii) decrease in renal blood flow.21 Ultimately, this leads to sodium and water retention, and increased systemic vascular resistance, which induces left atrial fibrosis and conduction block in the left atrium, and may potentially result in AF development.22