To reliably assess the impact of MHT on cardiac structure and function, only women using MHT for ≥ 3 years were included in the analysis. Data concerning MHT use was derived from UK Biobank fields 3546 (age last used MHT) and 3536 (age started MHT). Duration of MHT use was calculated by subtracting values in these two fields. Where women indicated that they were still currently using MHT, age at the time of imaging visit was used to determine duration. Duration of menopause was calculated by subtracting age at menopause (data field 3581) from age at time of imaging visit. To assess the impact of the “timing hypothesis”, a timing variable was created defined as age of menopause subtracted from age started MHT expressed in years.