Collagen deposition. A. Representative images showing collagen density of picro-sirius red stained right atrial myocardial tissue samples from non-diabetic (non-DM, n = 6) and diabetic (DM, n = 7) patients; yellow/brown staining represents myocardial fibers and red staining represents collagen fibers. B. Calculated collagen deposition was increased in DM group compared to non-DM group; collagen deposition reported as % of collagen in total tissue area/field from 21 fields/sample. Data are mean ± SEM; * = p < 0.05 vs. non-DM, unpaired t-test.