The majority of past clinical studies have shown that women who take estrogen substantially reduce their risk of developing and dying from heart disease. One or two studies demonstrate conflicting evidence, but they are far outnumbered by the positive reports. Results from a study showed that after 15 years of estrogen replacement, risk of death by CVD was reduced by almost 50 percent and overall deaths were reduced by 40 percent. Some researchers credit this reduction to oral estrogen's ability to maintain HDL and LDL at their healthier, premenopausal levels, through its interaction with proteins in the liver. In the latter case, both oral estrogen and the skin patch would be effective.
Studies are underway to determine which mechanism contributes most to a healthy heart.
Clearly, estrogen appears to benefit women at high risk for heart disease. The high risk group includes women with a strong family history of CVD, those with high blood pressure, smokers, and obese women. One study observed fewer cardiovascular deaths among estrogen users compared to nonusers. Women whose ovaries had been surgically removed had the greatest reduction of risk. The same study also confirmed, as expected, the link between smoking, obesity and cardiovascular disease.