This study demonstrates that use of MHT significantly impacts upon age-related reduction in LV and LA volumes. Recently published data detailing reference ranges for CMR imaging derived from a strictly healthy UK Biobank cohort has demonstrated that LV end-diastolic volume, end-systolic volume and LA maximal volume all decrease with advancing age , in keeping with findings from the never used MHT cohort. It is noteworthy, however, that use of MHT results in a much more marked rate of diminishment in LV and LA volumes, even after accounting for duration of MHT in addition to other confounders. Given that only 15% of women were using MHT at the time of CMR examination, it appears that this is an effect that persists, rather than being a contemporaneous result of being on treatment.