CHAPTER 5
The Heart and Circulatory System
In 1987 a group of courageous investigators made a remarkable and disturbing discovery that began a revolution in health care. Tobin and Steingart showed that cardiologists were treating the complaints of men and women very differently: doctors were twice as likely to ascribe a woman’s symptoms to hysteria or emotion as those of a man!1 Astonishingly, this pattern turned out to be true even when actors—one male and the other female—read an identical script describing cardiac symptoms to the doctor. Worse still, women whose exercise-thallium tests (a test that traces the distribution of blood through the coronary arteries at the peak of exercise) produced abnormal results were ten times less likely to be referred for cardiac catheterization, the definitive test for coronary artery disease (CAD).4 Subsequent studies have documented even more troubling news: women were receiving much more conservative treatment for their CAD than were men. While doctors prescribed medicines for women, they were sending men for aggressive interventions like clot-buster therapy, angioplasty, or coronary artery bypass surgery.5 Women’s CAD was—and is still—more likely to be managed by medication than by more aggressive intervention. Whether this is because doctors make more conservative decisions for female patients than they do for males or because women themselves choose more conservative therapy is still unclear. It is possible, some experts say, that women are having just the right treatment and that men are being treated too aggressively.
Whatever the case may be, women are less likely to receive recommended medications for management of the abnormal serum lipids (the fats carried in the bloodstream, like cholesterol and triglycerides) that are serious risk factors for heart disease. They are also less likely than men to receive medicines that have been proven to prolong life once a patient has had a heart attack.
Women were shocked by these findings. Happily, so were their physicians. Along with many of my colleagues, I was part of the revolution that resulted. The cardiovascular community of researching scientists and practicing physicians all rose to the challenge. Because of these findings more women were included in studies of heart disease. Until the 1990s, almost all the information we had about the cardiovascular system came from studies done exclusively on men—in spite of the fact that cardiovascular disease kills more women each year than all cancers combined! The new findings about men’s and women’s hearts have established one of the most important bodies of information in the new science of gender-specific medicine.
THE NORMAL HEART
The heart is a four-chambered muscular organ that receives blood from the veins of the body into its two right chambers. The lower right chamber, the right ventricle, pumps the blood to the lungs, where it is purified and resupplied with oxygen. The freshened blood then returns from the lungs via the pulmonary veins to the left side of the heart, the lower chamber of which, the left ventricle, then pumps it forward into the aorta and its branches, which distribute it throughout the body, where it purifies and nourishes our tissues and organs.
Like every part of the body, the size of the heart is proportional to the size of the whole person, so in general, women’s hearts are smaller than those of men. But women do not necessarily have smaller coronary arteries than men. Still, doctors have justified not sending women with severe coronary artery disease on to open-heart surgery because they have been told that women’s arteries are too small for bypass surgery. This is not the case; artery size in women varies widely, and most are entirely suitable for bypass. Women have had a higher mortality rate than men in bypass surgery, but this is because women were often diagnosed much later than men and were therefore older and sicker when they were referred for the operation. Now that doctors have learned to recognize the unique symptoms of CAD in women and how to test women more accurately, they diagnose them sooner. In centers where experienced surgeons perform bypass surgery on a daily basis, women now do as well as men in terms of survival.
Men, Women, and the Heartbeat
The heart beats because it generates its own electrical impulse in a special nodule of tissue, the sinus node, in the upper part of the right chamber called the atrium. This impulse travels throughout the entire heart along specialized conducting pathways, very much like electrical wiring, and stimulates the heart muscle to contract. An electrocardiogram (ECG) is a device that records the electrical activity of the heart, allowing the physician to see, among other things, whether the electrical impulse spreads through the heart muscle normally and whether each stage in the process is completed within a normal amount of time.
Each of the complexes that make up a heartbeat is composed of three different parts, and each part is named with a letter. Thus, a single cardiac impulse on the electrocardiogram has a P wave, a sequence of deflections called the QRS complex, and a T wave. The P wave represents the excitation of the upper chambers of the heart (the atria), the QRS complex that of the lower chambers (the ventricles), and the T wave the time it takes for the excited tissue to return to a resting state. The part of the ECG that indicates how long the heart takes to return to a resting state so that it can be excited by the next beat is called the Q-T interval. During the first part of that interval, the heart cannot be excited at all. During the last part of it, though, as it begins to return to a resting state, it is more excitable than usual and is susceptible to destabilization or capture by beats that arise in tissue outside the normal electrical network of the heart. These are called ectopic beats and are almost always premature: they take control of the heart before the next normal beat has time to develop.
Normal women are more likely than men to develop early or premature beats and even prolonged periods of very rapid abnormal beating (called arrhythmias). Why? Doctors have known for decades, since ECGs were first invented, that certain features of the ECG are normally different in males and females as soon as children achieve puberty. At puberty, boys’ Q-T intervals shorten under the influence of testosterone. This makes sexually mature men’s hearts more resistant to extra beats than women’s. The longer Q-T of women makes it more likely that an extra beat will capture the heart’s rhythm and start an arrhythmia. This vulnerability of women is influenced by hormonal shifts, perhaps profoundly. Many women complain that their heart palpitations become worse just before or early in their menstrual cycles. In fact, in one study of women with arrhythmias, 59 percent of patients reported that these periods of abnormal rhythm were associated with hormonal shifts—and 41 percent felt that hormonal shifts were the only precipitating factor. Estrogen can make the heart susceptible to abnormal rhythms; it intensifies the sensitivity of the heart to input from the sympathetic nervous system. (The sympathetic nervous system is part of the autonomic nervous system that controls the functions of the body that are not consciously regulated; the rate at which I breathe, for example, and the rate at which my heart beats are not something I consciously regulate; it happens automatically. The parasympathetic nervous system—the other part of the autonomic nervous system—slows the heart rate, while the sympathetic nervous system speeds it up.) In fact, the first oral contraceptive pills on the market, which had much higher estrogen concentrations than the pills we now use, increased abnormal beats in women with no underlying heart disease. In men, exercise is more often a trigger for abnormal rhythms; in women, hormonal fluxes or changes in levels are more likely to cause them.
Perimenopausal women (women who are still having menstrual periods but are also experiencing periods of estrogen deficiency as their ovarian function slows down) complain of palpitations more than younger women. Many times they have never had them before. This phenomenon too is hormone-related; low doses of estrogen often eliminate such symptoms.
Ironically, some of the very drugs developed to control and eliminate arrhythmias create unique problems for women. Why? Because many of them work by prolonging the time the heart takes to relax after each beat. In women, in whom this process already takes a relatively longer time, such a drug creates a paradoxical situation in which the patient is more likely to develop extra beats that often crescendo into arrhythmia. One of these arrhythmic patterns, which is particularly dangerous, is called torsades de pointes (a French phrase that literally means “revolving around a horizontal line” because of its characteristic chaotic pattern on the electrocardiogram), a potentially fatal event. Pharmaceutical companies are now trying to develop anti-arrhythmic drugs for women that diminish the instability of their heartbeat rather than increase it. Women are more likely to suffer sudden cardiac death than men during anti-arrhythmic therapy, and in one study of drug trials carried out between 1980 and 1992, women made up 70 percent of drug-related torsades de pointes.
The Heart Muscle: What’s Unique to Each Sex?
The bulk of the heart, which does the work of receiving and pumping blood to the body, is a unique kind of muscle. And just like the specialized cells that make up the electrical system of the heart, this tissue is different in men and women.
Cardiac muscle, like muscle everywhere in the body, is made up of individual units called contractile proteins. The composition of these proteins is different for males and females, which may explain why certain aspects of the efficiency with which the heart pumps blood differs between men and women. There are other differences too: individual muscle cells and groups of cells are held together in a mechanically well-integrated network by fiberlike, structural materials that form a kind of skeleton on which the muscle cells are arranged. Women have more of this supporting tissue than do men, which may account for the increasing stiffness of the heart in aging women, whose hearts are unable to work as efficiently as when they were younger: they have lost some of the important elasticity that lets the heart expand to receive blood between beats. Recent studies of congestive heart failure in women show that the cause might be increased stiffness or loss of elasticity of their heart muscle more than is the case for men, who are more likely to have a problem with weakened muscle fibers.
Some of these sex-specific differences in the composition of the heart are under the control of hormones. In animals, for example, thyroid hormone stimulates the growth of normal connective tissue (collagen) in the heart, and its effect is much more pronounced in males. Hypothyroidism (a disease in which the thyroid becomes less active than normal) is more common in women than in men. Women with hypothyroidism have much less elastic heart muscle than normal women.
CARDIOVASCULAR DISEASE:
HOW DOES IT DIFFER FOR MEN AND WOMEN?
High Blood Pressure (Hypertension)
Blood pressure is literally the force exerted on the wall of a blood vessel by the blood contained within it. Because there is more blood in the arterial system when the heart contracts, the pressure is higher; when the heart relaxes, the amount of fluid in the vessels is less. When your doctor tells you your blood pressure is 140 over 80, she means that when your heart contracts (the systolic blood pressure), the pressure in your arteries is equal to that of the weight of 140 milliliters of mercury (mm Hg) and that when your heart relaxes (the diastolic blood pressure) it is equal to that of 80 mm Hg. Women, at least until menopause, have lower blood pressure while they are awake than men of the same ages and a bigger dip in blood pressure at night. This difference emerges at the time of puberty. By about sixty, however, high blood pressure is more often found in women than in men. The protection that younger women enjoy thus seems to be related to ovarian hormone secretion, a concept that is borne out by animal studies: castrating young male rats reduced their blood pressure, while removing the ovaries of female rats caused their pressure to rise.
Officially, any blood pressure measurement that is higher than 140/90 mm Hg is called high and the patient has hypertension. More recently, doctors have found that 130/80 mm Hg is a safer limit for women and one at which the tissues of the body are best perfused with blood at an acceptable level of work by the heart.
The response of the heart to a need for increased work is different as a function of gender. When men develop high blood pressure, the major pumping chamber of the heart (the left ventricle) increases the size of muscle cells and the amount of connective tissue supporting those cells, so that it can push blood forward even with higher-than- normal pressure in the arteries. When this happens in a man, his ventricle becomes bigger, but the thickness of the wall does not increase. Women, on the other hand, meet the challenge by developing thicker-walled left ventricles; there is much less change in the overall size of the chamber, but it has a smaller interior surrounded by a thicker rim of muscle. This is called concentric left ventricular hypertrophy (LVH). Both sexes, then, increase muscle mass to pump blood against higher pressure, but the geometry of the bigger (hypertrophied) heart is different for men and women. This means that hypertensive women’s thicker-walled hearts may be less elastic than those of men’s, which may be a disadvantage for females. LVH is associated with a 50 percent higher rate of cardiovascular disorders in women than in men, and hypertension or high blood pressure is associated with stroke in 59 percent of women but only 39 percent of men.
About a quarter of all the people in the world have high blood pressure, and about 60 percent of them are women. Doctors never discover the reason for most hypertension, so hypertension with unknown causes is called essential hypertension. But in a small percentage of cases, particularly in patients under the age of thirty-five in whom there is no family history of high blood pressure, the causes are known. For example, in young people, the artery to the kidney may become narrowed, whereupon the kidney, experiencing lower-than-normal blood flow, begins to manufacture a chemical, angiotensin, that is a potent constrictor of arteries and makes blood pressure go up. Angiotensin also causes retention of salt and water, increasing the amount of fluid within the intra-arterial compartment and pushing pressure up still further. Eight times as many females as males develop this condition; doctors are not sure why.
Oral contraceptives are another cause of hypertension in women. With the older pills, which had a higher dose of estrogen than the present ones, about 5 percent of the women who took them developed high blood pressure, which never returned to normal in about 50 percent of those women, even after they stopped the pill. Modern versions of oral contraceptives have a lower dose of estrogen, and the risk of developing high blood pressure is less, though it is still about double the risk of women not on the pill. Women who use the tricyclic formula, because it has the lowest levels of progesterone, are at the lowest risk of all women using oral contraceptives for developing hypertension.
The situation seems to be quite different for women using HRT after menopause; in fact, in the older patient, estrogen may help to prevent hypertension, particularly in the patch (rather than the oral form).
Although much more study is needed to determine conclusively whether men and women respond differently to the hypertension medicines currently available, evidence suggests that they do. For example, in women, the use of a thiazide diuretic (a class of antihypertensives, of which Diuril is one) might help preserve bone structure at the same time that it reduces blood pressure because it tends to reduce the amount of calcium excreted in the urine. With ACE (anticholinesterase) inhibitors, another class of antihypertensive medications, cough was two to three times more common in women than in men. Women given a calcium channel blocker (still another class) are more likely than men to develop swelling of their ankles and legs. Men are less responsive than women to the category of antihypertensives that work by blocking the effects of the sympathetic nervous system on the heart. And last but certainly not least, an important side effect of many antihypertensive drugs for men is sexual dysfunction, which has really not been studied adequately in women.
Coronary Artery Disease
Until very recently, doctors and patients alike thought that coronary artery disease (CAD)6 affected only middle-age men. Most women still fear they will die of breast cancer and are aware of the importance of regular testing and early detection for survival. What they don’t know is that cardiovascular disease kills more women than all cancers combined and that for all of us—both men and women—CAD is the most important of all the illnesses that threaten our lives.
The fact is that half a million American women die each year of cardiovascular disease. Half of them die of CAD, and 100,000 of those deaths are premature. Alarmed by these statistics, women have begun urging doctors to pay more attention to their potential for heart disease. My own introduction to the issue came from Carol Colman, the medical journalist who walked into my office one day nine years ago and asked me to help her research and write a book about women and CAD. I wondered why she thought this necessary, what, I asked, was so different about CAD in women? It happened that Carol’s mother, who eventually died of CAD, had been misdiagnosed and inaccurately treated by physicians. Carol was convinced that women experienced the disease differently than men, and that doctors in general believed (wrongly) that CAD was not a significant problem in women. Even if women had CAD, doctors thought, it was not as serious for them, as they were protected by their hormones in a way that men were not. Carol believed that her mother’s illness and subsequent death could have been prevented, and she was determined that other women should not suffer the same fate.
What Is Coronary Artery Disease?
Like all organs, the heart muscle is fed by arteries that supply it with the blood it needs for work and survival. CAD results when a waxy substance called plaque (composed of cholesterol, clots, and other debris) accumulates in the arteries that supply the heart. Plaque narrows the inner diameter or lumen of the artery, and the flow of blood diminishes. If not enough blood reaches the heart tissue to supply it with the energy it needs, a portion of it dies. This is a heart attack, or myocardial infarction.
Several things besides plaque can cause a heart attack as well. If the surface of the plaque ruptures, a clot can form at the site of the break, further decreasing the space through which blood can pass. In other cases, the coronary artery itself contracts, narrowing the artery and restricting the blood flow to the heart. A critical degree of coronary artery constriction can be fatal in patients with other complicating factors: among these are cocaine (a powerful coronary artery vasoconstrictor) and sudden estrogen deficiency in women (estrogen helps keep coronary arteries dilated and able to bring critical amounts of blood to the heart muscle).
Do Women and Men Experience CAD in the Same Way?
Until recently, doctors believed that the actual experience of CAD was the same in both sexes. They believed that the symptoms of the illness, the factors that make some people more susceptible than others (risk factors), the way the disease is experienced over time (its clinical course), and the chances for recovery and survival (outcome) were similar if not identical for both men and women. (As I have said, this was because virtually all research on CAD had been done on men, and doctors were taught that the data could be applied to women without modification.) At the same time, and probably due to limited data about the illness in women, doctors (and many patients) believed that women didn’t get CAD until they were very old, and that when they did, the illness was milder than in men. Research done over the last ten years has taught us the opposite, that CAD is more lethal for females who suffer a heart attack (particularly those under fifty) than for males. And current gender-specific research on CAD in women has turned up a number of important findings.
Risk Factors
The risk factors and warning signs for CAD are generally the same for women as they are for men, but there are also important differences.
Serum Lipid Level: The fat in food cannot be used by the body until it has been processed by the liver and absorbed by the intestine. As a result of this process, several products of the fats we eat are carried in the blood. The principal ones are cholesterol and triglycerides. Cholesterol itself can be broken down into “bad” cholesterol or low-density lipoprotein (LDL), which is the type of fat that is deposited in the walls of arteries and is one of the principal ingredients of plaque. The other type is “good” cholesterol or high-density lipoprotein (HDL), which helps prevent plaque from forming. The two together are measured in the laboratory from a patient’s blood sample as total cholesterol (TC).
Men and women have different optimal levels of serum fats or lipids. While men can have HDL levels as low as 35 mg/dL of blood, women begin to have increased risk for CAD below levels of 45 mg/dL. HDL levels are particularly important in predicting resistance—or susceptibility—to heart disease in women: values below 30 are a matter for serious concern and treatment. Values above 60 mg/dL, on the other hand, are considered a protection against risk for CAD. For men, triglyceride levels can go as high as 400 mg/dL of blood without an increased risk of CAD; for women, optimal levels are under 200.
Diabetes: Diabetes is an important risk factor for both sexes for cardiovascular disease, especially CAD. It is more dangerous for women, however, as diabetes in women increases the risk of CAD four- to six- fold, even if a woman is young and/or premenopausal. In diabetic men, the risk of CAD is doubled.
Diabetes is important in other respects for cardiac patients of both sexes. Because diabetes affects and destroys nervous tissue, diabetic patients may not be warned by chest pain that they are having a heart attack, or that the supply of blood to their heart muscle is dangerously low. Men and women with diabetes, and their doctors, should take care to be alert to the signs and symptoms of CAD.
Age: Both men and women are more susceptible to CAD as they age. In general, though, the symptoms and signs of CAD begin to be apparent in men by the time they are thirty-five; in women, the disease is usually not symptomatic until they are about forty-five. Researchers have recently described a group of women between the ages of twenty and fifty with myocardial infarctions who did very poorly; they died twice as often in the hospital as did men of the same age. As is so often the case, these observations push us to reconsider our model of how heart attacks happen. The younger women who have heart attacks may suffer them because they have an abnormally high tendency to form blood clots in their vessels, including their coronary arteries, or because they have an exaggerated tendency to go into spasm, usually, but not always, because they are smokers. It is also probable that instead of rupturing, the plaque in the coronary arteries of these women erodes and attracts material that forms a clot that occludes the vessel.
Hypertension: Men and women have different consequences of high blood pressure, although for both it is a significant risk factor for CAD. Before menopause, women’s blood pressure is lower than that of same-age men, but as women age, their blood pressure increases at a faster rate than that of men. As I have explained, male and female hearts respond differently to hypertension: the left ventricle, which pumps blood out of the heart to supply the entire body, has a different pattern of enlargement in the two sexes. This difference is the result of hormones—it disappears in castrated rats with high blood pressure. We do not yet know if this information will lead to treating hypertension in humans with hormone therapy.
Obesity: Being 30 percent over ideal body weight increases the risk of both sexes for CAD. Men have greater risk than women at any given weight, however, because most of their fat is in the abdominal region, while women tend to collect excess fat in the buttocks and thighs. Abdominal fat is metabolized more actively in the liver than fat in other areas of the body, and it produces higher levels of serum cholesterol and triglycerides. Postmenopausal women, however, tend to resemble men in the way their fat is distributed. As they gain weight, their waistlines thicken, and they become more apple-shaped rather than pear-shaped. An important study of the effects of postmenopausal HRT in reducing women’s risk factors for CAD established that HRT seemed to slow weight gain and reduce the dangerous accumulation of fat around the abdomen. Obesity in general seems to be a risk factor for women. Investigators at Harvard who conducted a long-term study of a population of nurses observed that women with the lowest body mass index have the lowest probability of developing CAD. This finding is corroborated by studies in monkeys, which have shown that those fed the least amount of calories compatible with good nutrition lived the longest.
Family History: Having a first-degree relative (mother, father, sister, or brother) who dies of CAD before the age of fifty-five increases the risk for CAD in both men and women. For women, the risk is more serious if the relative is female. Such women should be evaluated each year for the signs of CAD; even children of families with a strong history of CAD should have their serum lipids monitored. No matter how young the patient, higher-than-normal levels of lipids should be aggressively treated with diet and exercise.
Menopausal State: While menopause is often blamed for (and can be the cause of) a whole host of ills, it does not seem to put aging women at increased risk for CAD. Risk for CAD in both men and women normally increases with age and increases still further if a person smokes, but menopause itself does not make women uniquely vulnerable.
Lifestyle Risk Factors
Smoking: Of all the things we voluntarily do that cause illness, smoking is the most lethal. Even one cigarette a day increases risk for both sexes. This fact makes it particularly dismaying to read that the greatest numbers of new smokers are teenage girls. Early smoking is particularly harmful for girls, as it actually stunts the growth of their lungs. Boys, on the other hand, seem able to smoke with greater impunity; unlike girl smokers, boy smokers do not have smaller lung volumes than their nonsmoking peers. Severe CAD in young women (under the age of forty) is almost always associated with smoking.
Lack of Exercise: Unfortunately from the standpoint of our physical fitness, the tremendous advances in science and technology over the past century have provided Americans with an increasing amount of leisure time and freedom from physical labor. The result is an epidemic of obesity: 97 million Americans are overweight, and the number has doubled over the last thirty-five years.
Exercise lessens the amount of sympathetic nervous system input to the heart, which in turn lowers heart rate, even at rest; exercise lowers blood pressure and causes the heart muscle to contract less vigorously with each beat. It doesn’t take much exercise to reduce the risk for CAD dramatically: just walking briskly for forty minutes a day three times a week can reduce the risk by 40 percent!
Stress: For both men and women, stress can literally be lethal. Some kinds of stress can be productive and health giving: a healthy sense of competitiveness, a sense of urgency to achieve, and a willingness to volunteer and excel at work are all useful and even desirable human traits. The kind of stress that kills is unique: it is best described as the emotional reaction that the sufferer has to problems that cause intense pain and difficulty and that apparently cannot be solved or relieved.
Many men are convinced that modern women have heart attacks because a growing number of them are working outside the home, which increases their stress levels. In fact, that is not the case at all. The Framingham Heart Study, one of the classic longitudinal studies (a study done over a relatively long period of time on the same group of patients) of CAD in both men and women, has shown that the women at lowest risk for CAD are those who find their work rewarding and are unmarried with no children.2 Women in what the Framingham investigators call “pink collar” jobs, who find their work unrewarding emotionally and/or financially, are at higher risk for CAD, while women in unrewarding jobs with primary responsibility for young children or infirm adults are at the highest risk of all. A study of married couples at a Volvo plant in Sweden found that when men and women arrived home, women’s blood pressure and heart rates rose as they crossed the threshold, while men’s fell!3
Both men and women, when faced with problems that cause them significant emotional duress and anxiety, experience an increase in the input of the sympathetic nervous system to the heart: their heart rates and blood pressure rise. If the stress is chronic, the adrenal glands begin to manufacture Cortisol to counter the effects of prolonged stress on the body. While it may mitigate agitation in response to stress, Cortisol also pushes blood pressure up and adversely affects the body’s metabolism. In fact, the emotion most commonly associated with a heart attack is a sense of pervasive hopelessness, which is also a common feature of long-standing stress. When I ask patients who have suffered a heart attack, “How do you think this happened to you?” every single one has answered, “I have been under a great deal of stress over the past few weeks/months/years.”
Use of Recreational Drugs: Although many patients refuse to talk about it, the use of illicit drugs is quite common. Cocaine is a particularly lethal substance for both men and women: it produces spasm of the coronary arteries (as well as other arteries, including those that supply blood to the brain). It can accelerate and/or destabilize the rhythm of the heart, producing stroke, heart attack, or sudden cardiac death even in very young, healthy individuals—including superbly fit athletes. Cocaine users would do well to remember that a person can often have CAD, even to an advanced degree, without symptoms. In addition to the drugs damaging addictive properties, cocaine can constrict arteries that are already partially occluded by plaque, with catastrophic consequences.
Testing for CAD
The most common test for CAD is the standard stress test. In this test, the patient is attached to monitoring leads, which record heartbeat, and to a blood pressure cuff, which measures blood pressure. The patient then walks on a treadmill as the incline and the speed are slowly increased, raising the heart rate to the maximum predicted safe value for his or her sex and age. The physician is able to tell from the changes (or absence of changes) in the ECG and blood pressure whether the heart is equal to the work it is being asked to do. While this kind of test is specific (accurately diagnosing a given kind of disease) and sensitive (actually detecting the presence of CAD) for men, it is neither specific nor sensitive enough for women and should not be used to screen for CAD in females.
ECGs in women are more likely to change during the course of a treadmill test even when the heart is actually quite healthy and is meeting the demands imposed on it (a false positive). Doctors do not know the reason for the unacceptably high incidence of false positives on treadmill tests in women. Women are more accurately tested with the stress echocardiogram, in which an ultrasound probe captures an image of the heart’s motion at rest and again at peak exercise. If the test shows that the heart motion is abnormal (a segment of the muscle moves weakly, doesn’t move at all, or paradoxically expands when the rest of the heart is contracting), the probability of CAD is extremely high.
Another kind of test uses radioactive tracers to assess the flow of blood to the heart during rest and exercise; it is equally accurate in men and women. But large breasts can interfere with the testing process; women with large breasts must be carefully positioned and the test evaluated by experts to make sure that the patient is not misdiagnosed with heart trouble when the problem is poorly transmitted signals.
Clinical Symptoms of a Heart Attack
The classic symptoms of a heart attack are a sensation of burning pain or of pressure (sometimes tremendous pressure) in the center of the chest. It may radiate down the left arm or down both arms and into the neck and jaw. For fully 20 percent of women with heart attacks, however, the symptoms are quite different: pain in the upper abdomen or back, intense shortness of breath, nausea, and profuse sweating. Such women may be misdiagnosed as having indigestion or a gallbladder attack. Their shortness of breath may be interpreted as an anxiety attack; many women, particularly if they are young, are sent home from emergency rooms with Mylanta and Valium, only to return in much more serious condition or when it is too late to help them.
Outcome of a First Heart Attack
The first heart attack is much more dangerous for women than for men. Contrary to the popular belief that CAD is more serious in men, studies show that 39 percent of women will die within the first weeks after their first heart attack, as compared with 31 percent of men. Women are also more likely than men to have a second attack within the following few years. Women who do survive are less likely than men to be able to return to their normal pre-attack lifestyles and are less likely to resume sexual activity. More females than males suffer from depression after a myocardial infarction (which may simply reflect the higher incidence of depression in women in the general population). A recent study reported that men with CAD had a better mood and outlook three years after their heart attack, but that women had better levels of physical recovery. The doctors who did this study felt that most of the men had a greater social support system than most of the women. While having a lot of help might keep the patient’s mood up, it might also make him more dependent and less likely to do the work needed for a return to full strength and health. On the other hand, a lack of friends and family to help care for the patient who is recovering from a heart attack might make her more susceptible to depression. Another interesting outcome of this study is that in both sexes recovery, both physical and emotional, seemed to plateau in year three after the heart attack. The researchers urged doctors and the families of heart attack victims to continue their efforts to restore patients to better levels of emotional and physical health for longer than just a few months.
Do Physicians Give Men and Women with Symptoms of CAD the Same Treatment?
As I pointed out in the beginning of this chapter, the unfortunate and undeniable fact is that men and women are still being treated differently by their doctors for the same diseases. This isn’t true only of heart disease: across the board, women are treated more conservatively than men for their illnesses. A woman with end-stage kidney disease, for example, is less likely than a man to get a kidney transplant. As disturbing as this was when it was pointed out for the first time in the late 1980s, it was more upsetting to read a 1999 paper by Kevin Schulman and his colleagues at Georgetown University College of Medicine indicating that even when patients with cardiac symptoms told identical stories, both their race and their sex influenced physicians’ decisions about whether to send them on for further testing.4 Black women were significantly less likely than white men to be referred for cardiac catheterization tests. The difference in the way physicians treat the two sexes was most marked for black women, who were the least likely to be sent on for definitive diagnosis on the basis of their histories. In addition, women are often offered only medication for their CAD, while men are offered thrombolytic therapy (clot-busting therapy that can open an occluded, or blocked, coronary artery if performed promptly after a heart attack) and angioplasty (a procedure in which a catheter, a thin tube, is inserted via an artery into the occluded coronary artery and a balloon at the catheter tip is inflated at the point of obstruction, compressing the obstructing plaque against the arterial wall). Several refinements and variations on the angioplasty procedure are now available. In some the plaque is vaporized by a laser beam and the fragments are harmlessly dispersed downstream from the point of obstruction. Stenting—or propping the artery open with a permanent tube—can be introduced to prevent reocclusion, and local radiation can prevent a new obstruction at the same site.
Open-heart surgery is also recommended more often for men. Even when women do have this kind of surgery, cardiac surgeons make different decisions: in female patients, surgeons less frequently choose the internal mammary artery for bypass of the obstructed site, even though it is superior to a vein because it is less likely to become occluded in the months and years after surgery. Studies from the United Kingdom and Israel as well as the United States have noted many of these discrepancies in the care of men and women with CAD. After citing them, the investigators consistently make the same statement: “Reasons for these differences remain obscure.”
In 1992 the Council on Ethical and Judicial Affairs of the American Medical Association published an important paper warning physicians that these striking differences in the way men and women were treated—not only for CAD, but across the board—reflected genuine bias about what care men and women could endure and should have.5 Whether the discrepancies are due more to the reluctance of women to accept more aggressive choices for treatment, or to physicians regarding women as less valuable than men (an opinion speculated on by the council in its landmark statement), or to an effort to protect women is unknown at this point.
If physicians do fear treating illnesses in women aggressively, such fears are unwarranted. Data from the National Heart, Lung, and Blood Institute, which collected the results of angioplasty procedures over a period of years and compared the results in men and women, showed that while women had a slightly higher mortality rate (2 percent higher), survival was at least 95 percent in both sexes. Although women had a higher mortality when they underwent coronary artery bypass grafting, this was because they were generally older and sicker than men, with more coexisting diseases, at the time of the surgery. If women with CAD are diagnosed early on and are referred promptly for bypass when appropriate, they do as well as men in the sophisticated hospitals that perform these procedures frequently.
Cardiac Rehabilitation
The limited data on gender differences in CAD recovery programs tell us what we might expect, that although physicians refer fewer female heart attack survivors (than males) to such programs women tend to participate in them as enthusiastically as men and to realize as many benefits from them.
In summary, cardiovascular disease is the chief killer of both men and women in the United States; not only are women not exempt from the disease, it is more severe in them, and women are more likely than men to die of their first heart attack. While men’s death rate from CAD is declining, women’s is not. Physicians are just beginning to be aware that the risk factors, clinical presentation, testing modalities, therapeutic choices, and consequences of CAD are not identical in men and women. In spite of scientists’ expanding understanding of these differences, a recent study revealed that many physicians do not counsel women patients, even when they are over sixty, about techniques to reduce their risk for CAD and omit essential testing to assess whether they have it or are at high risk for acquiring it. Men and women alike should know how to assess their risk for CAD and should be aware of the range of therapeutic options that are available in order to make an informed decision about treatment and rehabilitation. Finally, the entire community of women, as well as the physicians who care for them, should be aware of the regrettable tendency of doctors to minimize the cardiac complaints of women, attributing them to depression or hysteria. Such gender prejudice often results in late diagnosis of CAD, when it is far advanced and survival is less likely. Significant numbers of women, particularly young women, are sent out of emergency rooms with a diagnosis of panic disorder or hysteria, then go on to die from undiagnosed CAD. Prompt and accurate diagnosis and effective treatment of this, the chief killer of adults in this country, is the right of both men and women.
WHAT DOES THE NEW SCIENCE MEAN FOR YOU?
As a woman, how can I be sure that my doctor isn’t dismissing my complaints or treating my heart disease less aggressively than is warranted?
Unfortunately, as we’ve seen in this chapter, the odds are still against women receiving a prompt, accurate diagnosis and aggressive, optimal care for heart disease. To be an effective advocate for yourself under these circumstances, be sure to get organized before you see your doctor. Make a list of your complaints and the questions to which you need answers. If you have a specific problem, include a description of when it began, exactly what it feels like, what causes it, how long it lasts, and what makes it better or worse. Put together an orderly story that’s as accurate as you can make it. Keep it simple, concise, and clear.
If your doctor dismisses your complaints out of hand as psychosomatic and refuses to send you for diagnostic testing, challenge her. If she can’t collaborate with you to find out whether your symptoms indicate heart disease, she’s not useful to you. Continuing to be her patient may literally cost you your life, or at least valuable time before a correct diagnosis is made.
When you are given a treatment plan, question it very carefully, making sure you understand what medications you are being offered and how they are expected to work.
If I have an arrhythmia, what should I expect my doctor to know about the normal differences between my heart and circulation and a man’s?
Because the heart’s electrical system differs between men and women, your heart rate will be faster than a man’s, and your electrocardiogram will differ in some respects as well. You are more likely to perceive that you are having occasional extra beats of your heart, without their necessarily being more frequent than is normal. Nevertheless, you are more likely to develop long runs of rapid heart rates, particularly just before or on the first day of your menstrual period.
If you have been diagnosed with an arrhythmia, don’t be shy about telling your doctor that your bursts of rapid heart rate (the most common kind of this arrhythmia is called paroxysmal atrial tachycardia, by the way) are likely to occur just before you have your menstrual period. You are not imagining it—it’s due to the sudden drop-off of available estrogen during this time in your cycle. Using a low-dose estrogen patch during these few vulnerable days is a good way to eliminate this problem (and may also take care of your “menstrual migraine”—the headache many women experience during these low-estrogen days).
If you are perimenopausal (your menstrual periods have not stopped but now occur irregularly, and you experience some of the symptoms of menopause like hot flashes or difficulty sleeping) and you are suddenly experiencing bursts of palpitations and even longer runs of rapid heart rate, you need to find out whether they are a sign of heart disease and ask your doctor for appropriate diagnostic testing. Most likely, though, they are due to wildly fluctuating levels of estrogen—sometimes very high and at other times very low. Taking an oral contraceptive pill is an excellent way to smooth out these irregularities until you reach true menopause and your menstrual periods stop altogether.
If you are given a medication to control extra heartbeats, ask your doctor if the medicine was tested for safety in women! It’s unlikely that your doctor will know the answer, but women are unquestionably more likely to develop a potentially fatal arrhythmia when given certain drugs. If, after taking it, you feel no relief or even an increase in symptoms, consult your physician at once.
Should I ask my doctor to test my thyroid gland periodically to make sure it is not underactive?
Women have “stiffer” hearts than men as they age, because older female hearts have more connective tissue than younger ones. Hypothyroidism accelerates this “stiffening” process. Restoring the thyroid gland’s activity to normal is important if you have any signs of congestive heart failure (shortness of breath, rapid heart rates on minimal exertion that take a long time to return to normal, and/or swollen ankles). Ask your doctor to test your levels of thyroid-stimulating hormone and circulating thyroid hormone. If the tests show an underactive gland, small doses of thyroid replacement therapy can help lower cholesterol, control weight, relieve fatigue, and prevent the development of the “stiff” heart that makes relaxation of the heart muscle between beats more difficult and makes the heart function less efficiently.
Should I be worried about high blood pressure? What’s the best gender-specific treatment for me if it develops?
Before menopause most women are protected from high blood pressure, but after sixty more women than men have hypertension. The consequences are somewhat different for the two sexes.
Ask your doctor to take your blood pressure in both arms and, if the first value(s) are high, several times during the examination. Don’t underestimate the difficulty of getting a good reading: if your heart rate is slow and the measurement is made too quickly, the reading may not be accurate.
For most women with high blood pressure, doctors prescribe a kind of medication called a beta-blocker, an anti-anxiety drug, as a first choice. Not only does this choice reflect a conviction that a woman’s out-of-control emotions are causing her high blood pressure, but such drugs are more expensive than other antihypertensive medicines. Beta-blockers also have significant side effects in some patients: they tend to raise cholesterol levels and may put you at risk for asthma and depression (or at least unusual feelings of tiredness). A simple diuretic (or water pill) might be reasonable to try first. Another bonus of the diuretics is that they tend to preserve bone mass (by reducing the amount of calcium secreted in the urine).
After about three months, your blood pressure may go up again. Have your doctor adjust your medication and/or change the kind that you are taking.
If you develop high blood pressure while you are taking an oral contraceptive, stop taking it! Particularly if there is a history of high blood pressure in your family, ask your doctor for one of the tricyclic formula pills, which produce hypertension less frequently than other kinds of oral contraceptives.
Various kinds of antihypertensive medications are more likely to produce side effects in women, who are more likely to develop a cough on an ACE inhibitor and swelling of the ankles and feet on a calcium channel blocker.
Sexual dysfunction as a result of antihypertensive medicine has been well studied in men but not in women. If you notice any change in libido, in your ability to achieve orgasm, or in the intensity of your orgasm, ask your doctor to change your drug. By the way, one of the little-known consequences of diuretic therapy in women is that it may dry the vaginal lining and make intercourse uncomfortable. (Antihistamines can do the same thing.)
As a woman, what are the most important things I have to know about coronary artery disease?
There are very important differences between men and women in virtually every aspect of the experience of CAD.
• Diabetes is probably the most important risk factor of all for a woman; it removes any protection she has by virtue of her age or premenopausal state.
• Symptoms of an acute heart attack in one out of five women are not classic but involve epigastric pain, excessive sweating, and extreme shortness of breath.
• The optimal noninvasive testing modality (that doesn’t involve a radioactive tracer) for women is a stress echocardiogram; a simple treadmill test is neither specific nor sensitive enough in females to make it worth doing.
• After a myocardial infarction, women are much less likely than men to receive optimal therapy, which should include a beta-blocker, ACE inhibitor, an aggressive lowering of LDL cholesterol levels to below 100 mg/dL, and a daily aspirin. A low HDL (below 45) should be aggressively treated in women; as a risk factor, it has much more serious prognostic implications for women than for men.
• Recent data suggest that women with established coronary artery disease should not be started on hormone replacement therapy. But women who were on HRT before they developed CAD can safely continue it. These recommendations may change as data from the Women’s Health Initiative, an ongoing study supported by the National Heart, Lung, and Blood Institute of the NIH, accumulate and are reported to physicians.
• The waist-hip ratio is a more accurate indicator of risk for CAD than the body mass index. Be sure to ask your doctor to measure it for you, and if you have to lose weight, follow its improvement. (It should be 0.8 or less.)
• JoAnn Manson, who is now supervising the Nurses’ Health Study, points out that correcting poor lifestyle habits can lower the incidence of coronary artery disease in both sexes by 83 percent! Stop smoking (even one cigarette a day increases risk), pursue a reasonable and consistent exercise program, and pay particular attention to reducing stress in your life. As a woman, once you’ve had a heart attack, you are less likely than a man to be referred to a cardiac rehabilitation program, which is very important in returning you to full function. You are also more likely to be significantly depressed than a man and are less likely to return to your former level of activity, particularly to your pre-heart attack level of sexual activity. Ask your doctor to help put you in and keep you in an aggressive campaign to regain your health and confidence.