REN and atrial fibrillation: Nevertheless, our current methods of pharmacological modalities with reported immunomodulatory properties, including well-established classes of drugs e.g., drugs targeting the renin–angiotensin–aldosterone system (RAAS), statins, and vitamin D, have proven effective in reducing the overall risk of developing AF, the onset of postoperative atrial fibrillation (POAF), and reducing overall mortality among patients with AF.