TNF and atrial fibrillation: However, potential mechanisms include: (i) interaction resulting in RBBB between immune cells, fibroblasts, and/or cardiomyocytes, (ii) direct involvement of immune cells in the electrical remodeling of leukocytes resulting in RBBB (13, 37, 38), and (iii) In recent animal research, Dai et al. found that in RA rats, RA can cause atrial fibrillation (AF) by upregulating the production of inflammatory markers such TNF-α and IL-6 and increasing the number of cardiac fibroblasts.