SPP1 and obesity due to melanocortin 4 receptor deficiency: Macrophage‐derived SPP1 is a pleiotropic AF catalyst in HOMER mice (i.e. combining hypertension, obesity and mitral valve regurgitation) so that bone marrow transplantation from Spp1−/− to HOMER mice prevents left atrial enlargement (LAE), LV hypertrophy and ultimately AF inducibility and burden.