CMR is the most accurate and reproducible cardiac imaging modality and, when coupled with a large cohort size, permits detection of subclinical changes in cardiac structure and function. Whilst these subtle alterations may not result in any discernible impact to an individual at a single point in time, if they persist it is possible that they will eventually lead to prognostically relevant changes in cardiovascular outcomes. To our knowledge, this study is the first to explore the relationship between MHT use and subclinical changes in cardiac structure and function. Previous studies examining the impact of MHT on the cardiovascular system at the subclinical stage have focused on atherosclerotic burden as detected by cardiac computed tomography (CT). The most influential of these was a substudy of the Women’s Health Initiative which reported the coronary artery calcified-plaque burden was lower in women assigned to MHT than in those assigned to placebo . The more recent Early versus Late Intervention Trial with Estradiol (ELITE) study , designed specifically to investigate the “timing hypothesis” in relation to atherosclerosis progression in post-menopausal women, did not show any difference in plaque burden as assessed by cardiac CT in either early (<6 years) or late (≥10 years) menopause when compared to placebo although the authors did state that their sample size may be insufficient to detect any difference.