REN and atrial fibrillation: Beyond MMP-2 and angiopoietin-2 described above, this included: adiponectin, an anti-inflammatory hormone which has been shown to be independently associated with the development of AF [53] and predictive of mortality in the HF population [54]; Fatty acid binding protein-4 which has also been associated with cardiac function and remodelling [55]; and renin, which is known to play a crucial role in the renin-angiotensin-aldosterone system, and is associated with cardiac remodelling [56].