Reducing the risk of heart disease in women
Incorporating new research findings, the American Heart Association's updated guidelines make several changes in the previous recommendations.
The American Heart Association's 2007 update of its Evidence-Based Guidelines for Cardiovascular Disease Prevention in Women takes a longer view than the original 2004 document. “Since women develop heart disease later in life, we should look at lifetime rather than 10-year risk, and because one in two or three women develops CVD, we should start prevention across the life span,” says Nanette K. Wenger, MD, professor of cardiology at Emory University School of Medicine in Atlanta and an author of the update.
Certain recommendations, particularly those pertaining to lifestyle, now apply to virtually all women, she says. The update also incorporates new findings to fine-tune some interventions (e.g., the use of aspirin) and recommends against others (such as certain nutritional supplements).
The lifetime perspective of the new Guidelines means modifications in risk stratification. “We always had some concern that the standard risk assessment—the Framingham score and the newly developed Reynolds score—was looking only at short-term risk,” Dr. Wenger says. An index of the inadequacy of this approach, she notes, is the occurrence of subclinical evidence of heart disease in some women whose Framingham score puts them at low risk. The Guidelines propose three levels of risk:
• “High-risk” women have established coronary heart disease (CHD), cerebrovascular disease, abdominal aortic aneurysm, end-stage or chronic renal disease, or diabetes mellitus. Those with a 10-year Framingham global risk score >20% also fall into this category. These women are candidates for “more aggressive preventive therapy,” as outlined in the Guidelines.
• “At-risk” women have any of the major CVD risk factors or metabolic syndrome. “We added family history, subclinical markers of disease [such as coronary calcification], and two new things: low exercise tolerance and failure of heart rate to return rapidly to normal after exercise testing,” notes Dr. Wenger.
• “Optimal-risk” women have a Framingham score <10%, a healthy lifestyle, and no risk factors.
“The new lifestyle recommendations need to be highlighted,” Dr. Wenger says. The updated Guidelines focus on the same areas—notably diet and physical activity—as the 2004 version, but they provide more detail and in some cases contain additional suggestions.
Women are counseled not to smoke and to avoid environmental tobacco-smoke exposure. But the update specifies providing “counseling, nicotine replacement, and other pharmacotherapy as indicated in conjunction with a behavioral program or formal smoking-cessation program.”
The basic recommendation for physical activity remains a minimum of 30 minutes of exercise at a level of moderate intensity, e.g., brisk walking, most—and preferably all—days of the week. An addition, in the current update, is the prescription of a higher dose of physical activity (60-90 minutes, daily if possible) for women who are trying to lose weight or sustain weight loss.
In the dietary guidelines for all women, a variety of fruits and vegetables as well as whole-grain, high-fiber foods is still the mainstay. But several recommendations have been added: Consume fish (oily fish in particular) twice weekly, and limit alcohol to one drink and sodium to <2.3 g each day. While women are still counseled to consume no more than 10% of energy in saturated fat, the Guidelines say a better goal is 7%.
The recommendation of omega-3 supplementation for high-risk women is more detailed than before. In the 2007 update, the dose is specified: 850-1,000 mg of eicosapentaenoic acid and docosahexaenoic acid for women with CHD and 2-4 g for those with elevated triglycerides.
Risk factor interventions
Interventions to address major risk factors are largely unchanged from 2004: The update recommends the same lifestyle and pharmacotherapeutic measures to achieve the same lipid levels but go into more detail. There is one addition: To the recommendation that high-risk women reduce LDL to <100 mg/dL, the update adds that 70 is a “reasonable” goal for very-high-risk women with CHD, which may require LDL-lowering polypharmacy.
While the original guidelines recommended lifestyle modifications to achieve target BP of 120/80 mm Hg, the update spells them out in detail: weight control, increased physical activity, alcohol moderation, sodium restriction, and the addition of fresh fruits, vegetables, and low-fat dairy products to the diet. Thiazide diuretics are still advocated in the drug regimen of most women with BP ≥140/90 (130/80 in the context of chronic kidney disease or diabetes), unless contraindicated. But for high-risk women, the 2007 Guidelines specify beta blockers and/or ACE inhibitors/angiotensin receptor blockers (ARBs) as initial agents of choice. (The authors note that ACE inhibitors and ARBs are contraindicated in women who are or plan to become pregnant.)
The recommendations for prophylactic aspirin have been modified. “There are a lot of new data,” some of which show how benefits for women differ from those for men, adds Dr. Wenger. Besides advocating aspirin for high-risk women (unless contraindicated), the authors say that all women whose BP is controlled might consider daily aspirin if benefits are likely to outweigh the risk of GI bleeding and hemorrhagic stroke. In women 65 and older, these benefits include ischemic stroke and MI prevention, but younger women are protected only against ischemic stroke.
The dosage range for aspirin has been raised from 75-162 mg/day to 75-325 mg/day for high-risk women but drops to 81 mg daily or 100 mg every other day for those women at lower risk.
There are a number of important changes within the Class III or “do not use” category: interventions judged to be ineffective or harmful. Folic acid, which had previously been recommended for high-risk women with elevated levels of homocysteine, should not be used for primary or secondary CVD prevention at all (although the updated Guidelines affirm the use of folic acid during the childbearing years to prevent neural-tube defects).
The tentative recommendation against antioxidant supplementation (e.g., vitamin C or E) for CVD prevention “pending the results of ongoing trials” has become categorical, reflecting findings reported in the interim. The recommendation against hormone therapy for CVD prevention in the original guideline has been extended to include selective estrogen receptor modulators.
The American Heart Association's Evidence-Based Guidelines for Cardiovascular Disease Prevention in Women: 2007 Update appeared in Circulation (2007;115:1481-1501) and is available online at: http://circ.ahajournals.org/cgi/content/short/115/11/1481 (accessed December 10, 2007).
Mr. Sherman is a freelance writer in New York City.