The protective role of oestradiol against silent myocardial ischemia and hypertension risk in South African men: the SABPA study

Abstract

"Background: Oestradiol has a protective effect on coronary artery health in women but the effect it has on men, is controversial. A translational approach was followed to assess whether sex hormone levels are associated with silent myocardial ischemia (SMI) and hypertension risk over a 3 year period. Methods: Participants included 89 Black and 91White men (aged 21 – 63years) participating in bothphases of the Sympathetic activity and Ambulatory Blood Pressure in Africans prospective study. Fasting blood samples, ambu- latory blood pressure and 2-lead ECG recordings were obtained. Results: No difference in the levels of the various baseline serum T fractions between the two ethnic groups occurred. Oestradiol of the Black men increased by 54.2% comparedto a decrease of24.1% in the White men.Changes in total oestradiol (adjusted R2=0.33, β = − 0.31, p = 0.023) and free oestradiol (adjusted R2=0.34, β = − 0.33, p = 0.019) were inversely associated with changes in SMI in the Black men but not in White men. Baseline serum nitric oxide metabolites were inversely associated with Δ SMI in the Blacks only (adjusted R2=0.33, β = − 0.28, p = 0.047). Chronic SMI was associated with 24 h hypertension in Blacks [cut point 1.5 events: Area under the curve 0.71 (95% CI: 0.60, 0.82); p = 0.006; with sensitivity/specificity 44%/94%]. Conclusions: Chronic SMI events facilitated future ischemic heart disease in Black men. Up-regulated free oestradiol seems to be involved in the protection of the heart against SMI and hypertension risk in Black but not in White men. A similar protective role for testosterone could however not be shown."