Background:  There is conflicting information on the effects of oestrogen on the heart in women, especially those using postmenopausal hormone therapy. Whilst some studies reported a beneficial effect, others showed adverse outcomes. The interplay of lifestyle factors and type/timing of therapy remains to be clarified.
Aim:  The aim of this study was to determine the effects of lifestyle and hormone therapy on heart function and structure in postmenopausal women.
Method:  As part of a large longitudinal study of women randomly recruited from an urban population, the study assessed 410 suitable women by echocardiography in Year 1 and Year 5 of the study by two independent cardiologists.
Results:  In lifestyle characteristics, the difference in age and body mass (as markers of cardiovascular risk) was in favour of never‐users versus hormone therapy‐users. Using an arbitrary cut‐off ≥15% change for an effect, we found lifestyle factors had minimal effect on the two measured parameters – ejection fraction, left ventricular mass. Effects of hormone therapy were variable and mixed; greatest effect was found for an ‘early start’ of hormone therapy with oestrogen‐only preparation – the risk of reduced ejection fraction was decreased [hazard ratio (HR) 0.42, confidence interval = 0.17–1.03, P = 0.06] and risk of increased left ventricular mass was increased (HR 2.21, 1.09–4.49, P = 0.03).
Conclusion:  Our findings add to the evidence that oestrogen given to postmenopausal women has a mixed effect on the heart, with effect best shown when started early.