REN and atrial fibrillation: Atrial fibrillation and heart failure with preserved LVEF are increasing in prevalence and share common clinical features and pathophysiological mechanisms, with diastolic dysfunction, dysregulated neurohumoral regulation (activation of the renin-angiotensin-aldosterone system and atrial natriuretic peptide) leading to atrial dilation and fibrosis, resulting in isolated annular dilation (46).