Harvard Women's Health Watch

10 for 2010: 10 things you should know about heart disease

Women's unique heart risks are spurring changes in prevention and diagnosis.

Women and men share most risk factors for heart disease — including high cholesterol, inactivity, obesity, high blood pressure, and smoking — but there are some gender differences in its development, symptoms, and prognosis. Compared with men, women have a greater chance of dying from heart disease; they're twice as likely to have a second heart attack within six years of the first; and they don't fare as well after bypass surgery or angioplasty. On the other hand, women tend to develop heart disease about 10 years later than men.

What explains these disparities? The later onset of heart disease is probably due in part to the protective effects of ovarian estrogens, which are not lost until menopause. But because women develop heart disease later, they're more likely to have coexisting conditions, like diabetes, which can complicate treatment and recovery. Women also have smaller hearts and coronary vessels, which can make surgery more difficult. And some standard diagnostic techniques, such as coronary angiography, may be less effective for women.

Angiograms are good at finding cholesterol-laden plaques that bulge inward from vessel walls, forming blockages inside the arteries. That's how plaque typically forms in men. In women, it tends to grow more uniformly throughout the vessel walls and therefore may be undetectable by an ordinary angiogram. Heart attacks in men are usually caused by plaque rupture, which produces a clot that shuts down blood flow in an artery. Women are more likely to suffer from plaque erosion — they shed smaller pieces of plaque that generate a host of smaller blood clots. Moreover, women are more likely than men to have microvascular disease — narrowing or stiffening of the microscopic tributaries of the coronary arteries. These microvessels, too small to be seen on an angiogram, nourish the heart muscle and keep it healthy. Even when the main coronary arteries remain clear, microvascular disease can restrict the heart's oxygen supply, producing angina and other symptoms.

There's a lot more to learn about how women's hearts differ from men's, how they age, and how they respond to diet, exercise, stress, and other influences. Research is ongoing — so stay tuned. In the meantime, here are 10 things you should know about women's heart risks and how best to manage them.

1. Unfavorable cholesterol. The cholesterol (blood lipid) risk factors for heart disease are somewhat different in women than in men. A low level of "good" HDL cholesterol (below 50 milligrams per deciliter, or mg/dL) is a greater risk for women than elevated "bad" LDL cholesterol (the biggest lipid-related risk factor for men). High triglycerides (over 150 mg/dL) are also a greater risk factor for women, especially women with a waist measurement of 35 inches or more. Total cholesterol is less important than another number — the total-cholesterol-to-HDL-cholesterol ratio (total cholesterol divided by HDL cholesterol). The optimal ratio for women is less than 3.2. Risk in women is also associated with non-HDL cholesterol (total cholesterol minus HDL), which should be less than 130 mg/dL. What to do. Have a fasting lipid profile every five years. If your cholesterol levels need improvement, lifestyle changes come first — exercise, not smoking, weight control, and a nutritious diet that includes plenty of fruits, vegetables, and whole grains. Depending on your level of risk, your clinician may also recommend a medication (see "Medications you may or may not need").

2. The role of inflammation. Cholesterol is not the only indicator of heart disease risk. Evidence that inflammation plays a role in the formation of artery-clogging atherosclerosis has put a spotlight on C-reactive protein (CRP), a substance the body produces in response to infection and inflammation. Now there's a test for blood vessel inflammation called high-sensitivity CRP, or hsCRP. The Women's Health Study found that women with high hsCRP were about twice as likely as those with high LDL cholesterol to die from a heart attack or stroke. And women with normal LDL cholesterol but high hsCRP were at greater risk than those with elevated LDL and low hsCRP. As a result of such findings, the hsCRP test is now often used to estimate the likelihood of a heart attack. What to do. Healthy women with no known risk factors for heart disease don't need an hsCRP test. Nor do women at high risk who are already being treated. However, if you have normal cholesterol but other risk factors such as high blood pressure or a family history of heart disease, an hsCRP test might serve as a "tiebreaker" to help you decide whether to take a medication. Insurance usually covers the cost.

3. Blood pressure control. In both sexes, high blood pressure, or hypertension, damages the cells lining the coronary vessels and sets the stage for inflammation and plaque development. An optimal level is less than 120/80 millimeters of mercury (mm Hg). Up to age 55 or so, women are less likely to have high blood pressure than men. After that, their blood pressure typically rises more sharply than men's, and by age 70, about 80% of women have hypertension. What to do. If your blood pressure has crept above the optimal level, try lowering it with lifestyle approaches such as weight loss, increased exercise, moderate alcohol (no more than one drink per day), cutting back on salt, and following a healthy diet. If your blood pressure is 140/90 mm Hg or higher, your clinician may recommend a medication, usually a thiazide diuretic. (For more information, visit www.health.harvard.edu/womenextra.)

Heart disease prevention targets for women*

Risk factors

Targets

Lipids, lipoproteins

Total cholesterol

Below 200 mg/dL

HDL cholesterol

Above 50 mg/dL

LDL cholesterol

Below 100 mg/dL

Triglycerides

Below 150 mg/dL

Non-HDL-C (total cholesterol minus HDL)

Below 130 mg/dL

Blood pressure

Below 120/80 mm Hg

Body mass index (BMI)

18.5−24.9

Waist circumference (measured at navel level)

35 inches or less

Alcohol intake

1 drink or less/day

Exercise (moderate intensity, such as brisk walking)

30 minutes/day**

Sodium intake

Less than 2.3 g/day (about 1 tsp. salt)

*If you already have or are at high risk for heart disease, your target numbers may be different.

**Women who need to lose weight or sustain weight loss should aim for 60−90 minutes per day.

4. The need for exercise. More than 50 years of research has shown that the more physically active you are, the lower your risk of heart disease. In one study of postmenopausal women at risk for cardiovascular disease, those who were fit (able to jog at a rate of 5 mph or perform the equivalent) had a lower rate of heart attacks, strokes, and death — regardless of body weight — than those who were not fit. Exercise promotes many beneficial changes in the heart and the coronary arteries, including increased antioxidant activity and improved function of the endothelium (the cells lining the coronary arteries). It can raise HDL levels and lower triglycerides, changes that are especially important for women. It also helps ease mental stress — a risk factor for high blood pressure and thus heart problems. What to do. Apart from not smoking, exercise is probably the single most important thing you can do to reduce your risk for heart disease. For a list of resources on increasing activity and improving fitness, go to www.health.harvard.edu/womenextra.

5. Differences in symptoms. Both women and men may experience angina, the classic sign of heart disease, which causes chest pain, a cold sweat, nausea, and other symptoms. But women are more likely to report several less dramatic symptoms as well, including general discomfort, exhaustion, or shortness of breath under stress or during daily routines. Women are also more likely to experience Prinzmetal's angina, which occurs at rest (usually at night) and is caused by a spasm in a coronary artery. In both men and women, chest pain or pressure is often the first sign of a heart attack; arm pain, shoulder pain, and sweating are also common and unisex. But women are more likely to also complain of fatigue, nausea, back pain, dizziness, and palpitations. One study found that 84% of women (and 76% of men) experienced prodromal symptoms — early, heart-related warning symptoms (chest pain, arm and shoulder pain, shortness of breath, and fatigue) in the year before a first heart attack. What to do. The lesson here is, if you feel unusually tired, achy, or short of breath, check with your clinician to make sure it isn't heart disease.

6. Depression and the heart. The links between the mind and heart health are hard to quantify, but most health experts agree that psychological factors can contribute to cardiac risk. One of the most significant for women is depression. In the Nurses' Health study, depression was associated with an increased risk of fatal heart disease, including sudden cardiac death, even after correcting for other risk factors (including high blood pressure, high cholesterol, smoking, obesity, and inadequate exercise). It's not only that depression promotes heart disease; a heart attack can cause depression, which in turn raises the risk of a second heart attack. One way depression is harmful is that it can discourage a woman from taking care of herself — from exercising, avoiding cigarettes, eating well, and taking medications. Direct biological mechanisms may also be involved, including increases in inflammatory responses and blood clotting. What to do. If you're having a difficult time emotionally, your heart health is among the many reasons to consider seeing a mental health professional. Get a referral from your primary care clinician, or find a therapist through the National Alliance on Mental Illness, www.nami.org, 800-950-6264 (toll-free), or Mental Health America, www.nmha.org. For a list of mental health providers who accept Medicare, go to www.health.harvard.edu/providers.

7. Sleep and the heart. Poor sleep is associated with high blood pressure, atherosclerosis, heart failure, heart attack, stroke, diabetes, and obesity. In one study, middle-aged women who got no more than five hours of sleep per night over a 10-year period had a 30% greater risk for heart disease than women who averaged eight hours. Inadequate sleep has also been linked to coronary calcium, a component of atherosclerotic plaque. Another cardiovascular risk is a sleep-disrupting breathing problem called sleep apnea. And blood levels of several inflammatory markers (CRP, interleukin-6, tumor necrosis factor–alpha, and others) increase with poor sleep. What to do. Try to get seven to eight hours of sleep a night. If your sleep is chronically disturbed or inadequate or you often feel sleepy during the day, talk to your primary care clinician. Or, you can start here: www.nlm.nih.gov/medlineplus/sleepdisorders.html.

8. Assessing risk. For many years, experts have relied on a risk-assessment tool based on data from the Framingham Heart Study that estimates the risk of having a heart attack in the next 10 years by taking into account age, gender, smoking, cholesterol levels, and blood pressure. A measure known as the Reynolds risk score also takes into account hsCRP and family history and has improved predictive ability, especially for heart attacks in women. In one study, the Reynolds model reclassified into higher or lower risk categories nearly half of the women judged to be at intermediate risk by the Framingham model. What to do. To calculate your Framingham risk score, go to www.health.harvard.edu/heartrisk. If your risk is moderate — 5% to 20% — consider getting the hsCRP test, then reassessing your situation with the newer Reynolds model, which you can find at www.reynoldsriskscore.org.

9. Medications you may or may not need. Statins have become the treatment of choice for improving cholesterol levels. These drugs lower LDL, slightly boost HDL, and slightly lower triglycerides, by amounts that vary depending on the statin. Statins are an option if your cholesterol remains high despite lifestyle changes. But they're not for everyone. They may cause troubling side effects — especially muscle aches and, rarely, liver problems. And although they've been shown to reduce the risk of cardiovascular events (including fatal heart attacks) in women who already have heart disease, it's not clear whether women with high cholesterol but no symptoms of heart disease can also benefit. Other medications that target cholesterol levels are available and may be more appropriate in some circumstances. What to do. Talk to your clinician. If you have high triglycerides and high LDL, a class of drugs known as fibric acid derivatives may help. If you have low HDL cholesterol, one option is niacin, which both increases HDL and decreases LDL and triglycerides. Niacin usually must be given at a relatively high dose and monitored by a clinician.

Aspirin is a question mark for women. A daily aspirin has been shown to reduce the risk of a first heart attack in men, but the Women's Health Study found more equivocal results for women. Daily aspirin helped prevent ischemic stroke (the most common type), and it was somewhat effective in preventing heart attacks among women ages 65 and over. But for women under age 65, regular aspirin use was no better at preventing heart attacks than taking a placebo. Clearly, aspirin isn't a miracle worker, and it's not entirely benign either. Gastrointestinal bleeding and hemorrhagic stroke are risks of regular aspirin use. What to do. Talk to your clinician about the risks and benefits of aspirin for you. And keep in mind that a healthy lifestyle can be far more effective than aspirin in preventing heart attacks and strokes.

10. Improved diagnosis. The standard approach for assessing cardiac symptoms starts with electrocardiography (ECG) — at rest and on a treadmill (stress testing) — and may progress to coronary angiography, an x-ray that outlines any blockages in the coronary arteries. But ECG can miss heart disease in women, and angiograms can fall short, as noted earlier. What to do. Nuclear stress testing and stress echocardiography are more reliable than ECG and are available in many centers. Also, some women may need two other tests: intravascular ultrasound, which captures cross-sectional images of the artery walls, and coronary flow reserve studies, which measure blood flow in response to increased demand, often revealing whether the microscopic vessels in the heart wall are supplying it with enough blood. Both tests can be performed during angiography.

Last word

If you have worrisome symptoms, speak up. And make sure you have a clinician who listens and takes your concerns seriously. You may want to consider finding one at a center that specializes in women's health or at a heart center. For a list of such centers, visit www.health.harvard.edu/143.