Gender Differences and Heart Disease
Men and women experience heart disease differently
When it comes to heart disease, not only are the symptoms sometimes different for men and women but the disease itself may also be different.
There's an entertaining theory that men and women are from different planets. It's a not-so entertaining fact that men and women experience heart disease differently. It's not always clear why, but women are less likely to survive a heart attack than men. Women have a 50 percent greater chance of dying during heart surgery. And they're more likely than their male counterparts to develop heart failure, a weakening of the heart muscle that can be incapacitating and ultimately fatal.
Heart disease kills 500,000 women every year — 10 times more than breast cancer and more than all other cancers combined. It's also a leading cause of disability. Eight million women are living with it. While women develop cardiovascular disease about 10 years later than men, it's estimated that 1 in 10 American women 45 to 64 years of age has some form of heart disease, increasing to 1 in 4 women over the age of 65.
Historically, studies that set the standard for detection and treatment of heart disease were done mostly on men. But researchers found the results didn't always apply to women. Now, thanks to new research sponsored by National Institutes of Health National Heart, Lung and Blood Institute, more attention is being directed toward a better understanding of the unique features of heart disease in women.
Here's what scientists are finding out about gender differences and heart disease:
- Women with heart disease may have different symptoms than men. Women may experience the classic symptoms of gripping chest pain, sweating and shortness of breath, but they may also present with vaguer symptoms like generalized discomfort in the chest, breast, back, shoulders, jaw, neck or throat; indigestion; nausea; light-headedness; palpitations; sleep disturbances; and unexplained fatigue.
- Tests that reliably pick up signs of heart damage in men don't always work in women. These range from simple blood tests to exercise stress tests to standard angiograms. Some women don't have the strength to do a full exercise stress test and an incomplete one doesn't work the heart enough to yield truly useful results. Single-vessel heart disease, which is more common in women than in men, may not be picked up on a routine exercise stress test. Women with chest pain and other heart symptoms are more likely than men to have coronary microvascular disease even though tests show clear large coronary arteries. (See More About Women and Coronary MVD below.)
- Women tend to have heart attacks later in life. As a result, they're more likely to have other health issues. Symptoms of heart disease might be attributed to existing conditions, like arthritis or diabetes. Such problems as high blood pressure, high cholesterol and diabetes may make surgery a riskier proposition for them.
- Women have smaller hearts and arteries than men. One reason women haven't fared as well as men after bypass surgery and balloon procedures may be that their smaller vessels clog up again more easily after the procedures. In addition, surgeons performing bypasses in women are less likely to use an artery from inside the chest wall, because it's smaller and harder to work with, even though using the chest artery gives most patients better odds of long-term survival.
- There may be fundamental differences in the way women's hearts work. Researchers believe that women have a different intrinsic rhythm to the pacemaker of their hearts, causing them to beat faster. They also hypothesize that it may take a woman's heart longer to relax after each beat.
Several recent landmark studies have revealed that more women than men suffer from coronary microvascular disease. It's estimated that of the 8 million women in the United States with heart disease, as many as 3 million of them have coronary MVD.
The diagnosis of coronary MVD poses a unique challenge. Chest pain and other symptoms that the heart muscle isn't getting enough blood have traditionally signaled a narrowing or blockage in one or more of the heart's large arteries — a condition that's easily seen on an angiogram. But in about 50 to 60 percent of symptomatic women and 20 percent of men, the problem lies not in the major arteries but in the smaller branches which are virtually invisible on a standard coronary angiogram. Bottom line, coronary MVD, like traditional coronary artery disease, increases a woman's chance for a heart attack.
Researchers are just beginning to understand coronary MVD. The same risk factors that cause problems with the larger coronary arteries — heredity, age, race, blood pressure, blood cholesterol, obesity and smoking — may also contribute to coronary microvascular disease. Women appear to be more affected by certain factors, such as high blood pressure, smoking and diabetes than men. In addition, there are a host of other risk factors unique to women. Only women become pregnant, experience menopause and are prescribed contraceptive pills and postmenopausal estrogens.
Theories on why the disease may differ in women include the following:
- Low levels of estrogen. Because estrogen plays a role in processing nitric oxide, which helps arteries function properly, the endothelium may suffer when natural estrogen levels wane.
- More inflammation (an overreaction by the immune system). Inflammation stimulates the body to use cholesterol in the bloodstream as a band-aid to cover up irritated areas in the blood vessels.
- Higher incidence of anemia. Anemia is thought to slow the growth of cells needed to repair damaged blood vessels.
- Lower levels of hemoglobin (a protein in red blood cells that carries oxygen). Hemoglobin deficits may starve the heart muscle and also reduce nitric oxide levels.
- Lower HDL ("good" cholesterol) levels. There is evidence that having low HDL is more predictive of the development of coronary heart disease in women than high LDL ("bad" cholesterol) levels are.
Findings so far have raised as many questions as have been answered, but the work represents a good start in zeroing in on ways to tailor diagnosis specifically for women. Progress has already been made in educating doctors about symptoms that, in the past, were under-recognized or misinterpreted in women. Scientists are focusing on how diagnostic and treatment techniques may need to be changed to improve women's outcomes.
Don't Ignore Symptoms Coronary Disease
Coronary microvascular disease is tough to diagnose. If you are experiencing symptoms that concern you, don't ignore them. You need to continue a dialog with your doctor until you're both satisfied.
If your doctor suspects you are at risk for heart disease, there are a number of traditional diagnostic tests used to look for blockages that affect blood flow in the large coronary arteries (coronary artery disease or CAD). However, standard tests for CAD, like electrocardiograms, exercise stress tests, echocardiograms and angiograms don't always detect coronary microvascular disease (MVD), a disease where the smallest coronary arteries are affected.
As more is learned about coronary MVD, new protocols and tests are emerging.
Self-Reported Physical Fitness Scores Since symptoms of coronary MVD often first appear during routine daily tasks, a questionnaire called the Duke Activity Status Index (DASI) that asks about an individual's ability to perform certain daily tasks can prove useful. It yields information about how well blood is flowing through coronary arteries and also helps doctors select appropriate next steps.
Duke Activity Status Index
Circle the points for a question only if you can answer "Yes, with no difficulty." Add up the circled points. The lower the score, the greater the risk. Total scores of 4.7 or below are considered higher risk.
Stress tests are performed to determine whether there's enough blood flow to the heart during physical activity. They involve performing simple exercise, usually with a treadmill or a stationary bike. Sometimes pharmacological agents are used to simulate the heart's reactions to exercise. Standard stress tests tend not to be as reliable in women as in men, but using imaging such as echocardiograms or nuclear scans in conjunction with an exercise stress test improves their accuracy.
- Adensosine Coronary Flow Reserve and Acetylcholine Endothelial Function Test with Cardiac Magnetic Resonance Imaging (MRI) This is a pharmacological stress test. During the two-step test, the drug adenosine, which causes the small vessels of the heart to dilate, is injected into one of the coronary arteries and the amount of blood flow is measured. Next, the drug acetylcholine, which causes dilation in the large arteries, is injected and the amount of blood flow is again measured. The superior resolution of magnetic resonance imaging is used to get images of the beating heart and to look at its structure and function. MRIs can show poor blood supply to the innermost areas of the heart and can detect changes in the small coronary blood vessels. If either test shows decreased blood flow to the heart muscle, a diagnosis of microvascular disease can be made.
- Dipyridamole Positron Emission Tomography (PET) This cardiac PET scan also shows how much blood flow the heart receives at rest and under stress. During the first stage, fluorodeoxyglucose (FDG) is administered while the patient is at rest. The images that are produced from this first PET scan are checked with a second PET scan after the patient is administered dipyridamole, a drug that produces an effect in the body similar to the effects of strenuous exercise.
- Doppler Wire Coronary Angiogram The most definitive test for microvascular disease is a special type of coronary angiogram used to measure coronary artery flow reserve or coronary reactivity. It involves threading an ultrathin wire with blood-flow sensors at the tip deep into a coronary artery (called cardiac catheterization). Blood flow in the artery is then measured before and after injections of one or more medications to cause the microvessels to dilate. The smaller the change in pressure and flow, the stiffer the vessels. This test is done only at a small number of cardiac centers in the country. Cardiac catheterization procedures are invasive and expensive, but the risks of doing them have to be weighed against the risks of not receiving an accurate diagnosis.
A great deal remains to be learned about coronary MVD, especially in women. In the meantime, there are some basic strategies that you can use to get an accurate diagnosis and the best possible medical care. Listen to your body and believe in your instincts. If you feel strongly that something is wrong but your doctor can't find a problem, get a second opinion. Find a specialist who is familiar with coronary MVD. Ask questions. If you don't fully understand the answers, ask more questions until you do. There's nothing more important than your health. By balancing assertiveness with respect for your physicians, you can get the information you need.
Lifestyle Changes for Recovery Success
If you've received a diagnosis of coronary microvascular disease, getting adequate blood flow to your heart is critical. Lifestyle changes are the most effective treatment.
Treatment goals for coronary MVD are three-fold — stop it from getting worse, improve quality of life by relieving symptoms, and prevent a heart attack. Standard invasive treatments for coronary heart disease (CAD), like angioplasty, stenting and bypass surgery, aren't used to treat coronary MVD. Instead, treatment focuses on reducing risk through managing underlying conditions.
Talk to your doctor about your risk factors for heart disease and how to control them.
- Know your numbers — ask your doctor for these three tests and have the results explained to you.
◦ Lipid profile. This test measures total cholesterol, LDL cholesterol (often called bad cholesterol), HDL cholesterol (often called good cholesterol) and triglycerides (another form of fat in the blood).
◦ Blood pressure.
◦ Fasting blood glucose. This test is for diabetes.
- Know your body mass index (BMI) and waist circumference. BMI is an estimate of body fat that's calculated from your height and weight. You can use the National Heart, Lung and Blood Institute's online BMI calculator to figure out your BMI. To measure your waistline, stand and place a tape measure around your middle, just above your hipbones. Measure your waist just after you breathe out.
- Know your symptoms and how and when to seek medical help. Be able to describe the usual pattern of your symptoms. Know how to control them.
- Know which medicines you take and when and how to take them.
- Know the limits of your physical activity.
Make heart-healthy lifestyle changes to reduce your risk factors. You can't control some risk factors of heart disease, like age and family history. But you can take aggressive steps to lower or control other risk factors, like high blood pressure, overweight and obesity, high blood cholesterol, diabetes and smoking.
Follow a heart healthy eating plan. Two heart healthy eating plans are the Dietary Approaches to Stop Hypertension (DASH) diet (for people who have high blood pressure) and the Therapeutic Lifestyle Changes (TLC) diet (for people who have high blood cholesterol).
- Increase your physical activity. Aim for at least 30 minutes of moderate-intensity activity on most, and preferably, all days of the week. If you're trying to manage your weight and keep from gaining weight, try to get 60 minutes of moderate-to-vigorous-intensity physical activity on most days of the week.
- Quit smoking, if you smoke.
- Lose weight, if you're overweight.
- Learn ways to avoid or cope with stress
Take medicines as your doctor prescribes.
- Standard anti-angina drugs that work by relaxing blood vessels, such as nitroglycerin, can help ease symptoms. Nitroglycerin is prescribed to relax blood vessels, improve blood flow to the heart muscle and treat chest pain.
- High cholesterol and high blood pressure are almost certainly among the causes of microvascular disease. In addition to diet and exercise, lipid-lowering drugs, like statins, can be used to improve cholesterol levels and beta blockers, calcium-channel blockers or vasodilators to lower blood pressure and decrease the heart's workload.
- If you have diabetes, check your blood sugar level every day to make sure your medicines and diet and exercise are working to keep it in a normal range. Two out of three people with diabetes die from heart disease and stroke.
- Low-dose aspirin can be used to help prevent blood clots or control inflammation. Other blood clot reducers include anticoagulants and antiplatelets.
Treat anemia. It slows repair of damaged blood vessels. Anemia treatment depends on the cause and can involve iron supplements, folic acid or hormone injections, and blood transfusion or antiplatelet drugs.
Although a great deal of new knowledge about coronary MVD has been uncovered in the last decade, more work needs to be done. Watch for new findings from the federally financed Women's Ischemia Syndrome Evaluation (WISE) study.
This article reprinted with permission from Second Opinion, a public television health program hosted by Dr. Peter Salgo and produced by WXXI (Rochester, N.Y.), West 175 and the University of Rochester Medical Center.