Testosterone-to-estradiol ratio and platelet thromboxane release in ischemic heart disease: the EVA project

Background Data on the interplay between sexual hormones balance, platelet function and clinical outcomes of adults with ischemic heart disease (IHD) are still lacking. Objective To assess the association between the Testosterone (T)-to-Estradiol (E2) Ratio (T/E2) and platelet activation biomarkers in IHD and its predictive value on adverse outcomes. Methods The EVA study is a prospective observational study of consecutive hospitalized adults with IHD undergoing coronary angiography and/or percutaneous coronary interventions. Serum T/E2 ratios E2, levels of thromboxane B-2 (TxB(2)) and nitrates (NO), were measured at admission and major adverse events, including all-cause mortality, were collected during a long-term follow-up. Results Among 509 adults with IHD (mean age 67 +/- 11 years, 30% females), males were older with a more adverse cluster of cardiovascular risk factors than females. Acute coronary syndrome and non-obstructive coronary artery disease were more prevalent in females versus males. The lower sex-specific T/E2 ratios identified adults with the highest level of serum TxB(2) and the lowest NO levels. During a median follow-up of 23.7 months, the lower sex-specific T/E2 was associated with higher all-cause mortality (HR 3.49; 95% CI 1.24-9.80; p = 0.018). In in vitro, platelets incubated with T/E2 ratios comparable to those measured in vivo in the lowest quartile showed increased platelet activation as indicated by higher levels of aggregation and TxB(2) production. Conclusion Among adults with IHD, higher T/E2 ratio was associated with a lower long-term risk of fatal events. The effect of sex hormones on the platelet thromboxane release may partially explain such finding.