According to a new study, researchers have evidence that a higher proportion of male to female sex hormones was associated with a significantly increased relative cardiovascular disease risk. In an analysis of data collected from more than 2,800 women after menopause. The researchers caution that theirs was an observational study that was not designed or able to show or prove cause and effect. They suggest that having a more male-like hormone profile seems to increase the risk of heart disease and strokes in postmenopausal women independent of other risk factors.

A woman's sex hormone levels and ratios of them isn't something that physicians regularly check. Decades of research have shown that, prior to menopause, women have lower heart disease rates than men, and because estrogen levels drop sharply after menopause, physicians once thought that replacing estrogen would reduce cardiovascular disease risk.

That idea was essentially upended when results of a landmark women's health study reported in 2002 showed that female replacement hormones weren't necessarily protective and could raise the risk of strokes, blood clots, and heart disease. Some experts have suggested that those results may have been skewed or exaggerated by the use of older forms of hormone therapy and the fact that it was given many years after menopause in the trials.

Additionally, researchers had not focused on the body's natural levels and ratios of sex hormones as an index of risk in their own right. The estrogen used in the most common hormone therapy preparation is in a different chemical form than that of the body's natural premenopausal estrogen, estradiol. At an initial visit that took place between 2000 and 2002, researchers took blood samples and measured levels of testosterone and estradiol.

Over 12 years of follow up, the women had 283 instances of cardiovascular disease, including 171 instances of coronary heart disease and heart attacks, 88 strokes and 103 instances of heart failure as determined by medical records, hospitalizations, telephone interviews and death certificates.

Among the postmenopausal women in this study who were all free of cardiovascular disease at the beginning, almost 5% developed the new cardiovascular disease within five years. When the researchers compared testosterone and estradiol levels to instances of heart and cardiovascular diseases, they found, in general, that higher testosterone was associated with increased risk and higher estradiol levels with lower risk. 

After adjusting the results to account for multiple other heart disease risk factors including age, body mass index, education, diabetes and blood pressure, they looked at the ratio of testosterone to estradiol ¾ essentially dividing the testosterone level by the estradiol measurement. For every standardized unit increase in the ratio of testosterone to estrogen, there was a 19% increase in cardiovascular disease risk, a 45% increase in coronary heart disease risk and a 31% increase in heart failure risk.

As to these hormones may affect risk,  there is ample evidence from other studies in women that testosterone can raise blood pressure and contribute to insulin resistance, which is harmful effects, whereas estrogen relaxes blood vessels and lowers bad cholesterol levels, which tend to be good things for the heart and vascular systems.