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Over 80 percent of women use hormonal contraception at some point in their lifetime. However, the use of contraceptive hormone therapies to prevent pregnancy—birth control pills, patches and vaginal rings—may heighten the risk of heart problems or stroke in certain women, particularly those who smoke, are over 35 years old or have existing cardiovascular risk factors.
As with all medicines, contraceptive hormones must be selected and initiated upon evaluating the risks and benefits for each patient, according to a review article published in the January 20, 2009, issue of the Journal of the American College of Cardiology (JACC).
“As women use these therapies more frequently, and for longer periods of time, there is an urgent need to better understand and minimize associated cardiovascular risks,” says C. Noel Bairey Merz, M.D., F.A.C.C., F.A.H.A., director of the Women's Heart Center, Cedars-Sinai Heart Institute and co-author of the study. “Women at high risk for cardiovascular problems, especially those who smoke, should consider alternative forms of contraception. Those with other cardiac risk factors such as hypertension or elevated cholesterol can consider use with monitoring under the advisement of their health care provider.”
The impact of reproductive hormones on cardiovascular health is complex. Low estrogen levels and irregular menstrual cycles have been found to elevate the risk of coronary atherosclerosis (the thickening and hardening of the inside walls of the arteries) and adverse cardiac events (e.g., heart attacks, strokes or deaths due to heart disease). At the same time, supplemental estrogen can increase the risk of blood clots, which can lead to stroke.
According to the authors, while older formulations of contraceptive hormones can slightly increase blood pressure, newer generation contraceptive hormone formulations appear to carry lower cardiovascular risks and are as safe and effective in preventing pregnancy. However, further study is needed.
“The newer formulations have lower doses of estrogen, which is safer in terms of lowering the risk of blood clots,” says Dr. Merz. “They also tend to use a progestagen—hormones that produce effects similar to those of progesterone—which are expected not to raise and may even slightly lower blood pressure.”
Recent data reveal that since 2000 the death rate from cardiovascular disease has increased in women between the ages of 35 and 44 years compared with decreases in all other age groups. Research points to higher rates of obesity and smoking and declines in physical activity, as well as a concomitant increased use of oral contraceptives among this group of women (from 4 percent to 17 percent) during the same timeframe.
The article provides an overview of clinical studies of risk and cardiac events in women using contraceptive hormones, as well as guidelines for prescribing these therapies in women with existing cardiovascular risk factors (e.g., high blood pressure, high cholesterol, diabetes). The report also discusses the impact of hormonal contraception on specific mechanisms underlying cardiovascular disease, including atherosclerosis, thrombosis (formation of a clot inside a blood vessel), vasomotion (blood vessel constriction) and arrhythmogenesis (irregularities in the heart beat).
“Health care providers must evaluate each woman’s risk factors, especially those related to cardiovascular health, prior to starting any contraceptive therapy,” says Chrisandra Shufelt, M.D., M.S., assistant director, Women's Heart Center, Cedars-Sinai Heart Institute and co-author of the study. “Although pre-menopausal women have a much lower risk of cardiovascular disease, routine screening for potential problems and follow up is important.”
Drs. Merz and Shufelt report no conflicts of interest.
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