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Gender

By: Kavanagh, Terence, Take Heart! Key Porter Books 1998, page 36-40

Even though younger women possess some gender-linked protective factor, we are still left with the unhappy statistic that coronary heart disease accounts for 250,000 deaths each year among American women. It is the third leading cause of death in women aged 35 to 39 years, the second in those aged 40 to 64 years, and first in women aged 65 and over. However, because of the greater male-to-female ratio of cardiac deaths in the age groups 35 to 54, most of the research into the causes of coronary disease has involved men only. After all, if you want to learn as much as you can about a disease, it makes good sense to start by observing the group in which it is most prevalent. In short, you fish where there are the most fish. Or as a famous bank robber replied when asked why he robbed banks, " Because that's where the money is."

But is it valid to assume that the conclusions gained from these studies on men also apply to women? In particular, do the same risk factors apply? With certain reservations, the answer would appear to be yes. What are these reservations?
Diabetes is a powerful risk factor in women. Women diabetics have a four-to sixfold risk of developing heart disease compared with nondiabetic women; men with diabetes have a twofold risk compared with nondiabetic men. In effect, diabetes completely erases the protective effect from coronary disease that women enjoy in their premenopausal years.

Younger women, often in their teenage years, are smoking in increasing numbers, possibly because they consider it "trendy" or because they fear gaining weight; yet cigarette smoking is a particularly dangerous risk factor for women under the age of 50 years. In this age group, those who smoke more than 15 cigarettes a day are four and a half times more likely, and those who smoke more than 30 cigarettes a day, ten times more likely to suffer a heart attack than nonsmokers. In fact, even women who are "light smokers" (one to four cigarettes daily) have more than twice the risk of coronary artery disease than nonsmokers. In short, the woman who smokes like a man will die like a man - or even more so! As in men, ex-smokers appear to be at little or no risk. Unfortunately, the evidence is that women find it harder to stop smoking than men. If, in fact, smoking is more addictive in women than in men, then we should be targeting women, and in particular younger women, in our antismoking campaigns. On the other hand, if the woman stops smoking, but the spouse doesn't, she is still at a 20 - 30% risk for a heart attack from inhaling second-hand smoke. And finally, as we have seen, smokers who are on the pill have as much as 20 times the risk as nonsmokers on the pill. This may have to do with the fact that cigarette smoking alters the estrogen metabolism in premenopausal women. The resulting lower estrogen levels cause premature menopause, which in itself increases the risk of coronary heart disease. All in all, because of the high prevalence of smoking among women, eliminating this habit would probably be the single most effective method of reducing their incidence of heart disease.

Hypertension is now recognized to be a strong risk factor for coronary heart disease in women, and yet 30% of women over the age of 65, the age group most susceptible to heart disease, are hypertensive. Studies in Australia, Europe, and the United States have also demonstrated that appropriate treatment results in a significant reduction in death from stroke and heart disease in patients up to 84 years of age, with women benefiting to the same degree as men.

We will examine the influence of blood cholesterol levels on coronary disease in more detail in Chapter 4. Suffice it to say at this stage that in men there is a strong association between high total blood cholesterol levels and coronary heart disease. Does the same apply to women? The answer seems to be yes, except that there is a greater need to look at two other measurements, namely high density lipoprotein cholesterol (HDL-C), the "good" cholesterol, and triglycerides, the other form in which fat is carried in the blood. Premenopausal women have more of their cholesterol in the HDL form than men, and therefore a total cholesterol reading which would be considered a risk for a man may not be for a woman, for the simple reason that it is counterbalanced by the high HDL-C content. After menopause, however, when estrogen production begins to fail and HDL-CC levels fall, then that same total cholesterol reading becomes a risk factor. HDL-C readings are therefore essential in women if we are to interpret the importance of the total cholesterol measurement. High triglycerides, often associated with obesity and diabetes, when they are accompanied by low levels of HDL-C, may be a better predictor for heart disease in women than men.

There are conflicting reports as to the risk of obesity in women, although these disagreements may be explained by the findings that the pattern of fat distribution is more relevant than the actual amount of excess fat. Women tend to put on weight around the hips, so that, even if they are obese, their hip measurement remains greater than their waist. Men tend to put on weight around the waist; all too often their belly protrudes well above the belt. It is the male pattern, whether in a man or a woman, that is associated with coronary disease. Abdominal obesity in a woman is associated with high blood pressure, high triglyceride and reduced HDL-C levels, and Type II diabetes - a cluster of conditions first given the attention grabbing label, the "Deadly Quartet," by the American physician Dr. Norman Kaplan.

There has been little investigation into the effects of such factors as family history or psychosocial interaction on women. Nevertheless, from the Framingham and other studies, the following trends have emerged. A family history of premature heart disease ( a heart attack in a father or brother under the age of 55 years, or a mother or sister under the age of 65 years) carries an increased risk, as it does for men. However, there is some suggestion that the risk is stronger where the history is on the female side. Contrary to popular impression, the incidence of CHD is not higher in successful hard-driving career women. Rather it is greater in housewives, and also in those women who work in lower-paid jobs, in which they may have little or no control or authority.

There is not a great deal known about the effect of environmental stress on women compared with men. However, one intriguing research project has been carried out on a group of premenopausal macaque monkeys. The females of this species have a definite social status within their group and attempt to maintain or even improve that status (keeping up with or surpassing the Joneses, as it were). Over a ten-year period, batches of monkeys were exposed to stress by reducing their status and exchanging their dominant role for a more subdominant, submissive role. This change was achieved by putting them at the back of the line as they approached the water or food containers and depriving them of their rightful place to perch. All of the stressed females showed a marked drop in their HDL-C. Not only that, but they also developed severe coronary atherosclerosis. No such changes were observed in the non-stressed females. Further careful study revealed that the stressed females also showed an impairment of ovarian function, with the result that they had significantly lower levels of estrogen. This reduction in estrogen levels correlated closely with the fall in HDL-C and the appearance of severe coronary atherosclerosis.

We do know, however, that more than 60% of all women have one or more of the known major risk factors. There is every reason to believe that, having identified these individuals, we should be able to take preventive measures that will be every bit as successful as in men. Unfortunately, we do not seem to have been as able to convince women of this as we might like to think. For instance, over the past 25 years smoking among men has declined by about 50%, whereas in female teenagers it has increased. Obviously, when it comes to lung cancer and heart disease, we have been talking only to men. Contrary to the facts, women over 65 years continue to believe they are more likely to die from cancer than from a heart attack. The reality is that one in seven women between the ages of 45 and 64, and one in every three over the age of 65 have already developed evidence of coronary disease. We can only hope that future health promotion strategies will be designed with women in mind.

CCRF would like to thank Dr. T. Kavanagh for his contribution to the Website.

The articles, on the Cardiac Health Foundation of Canada website, are presented with the understanding that the Foundation is providing information only and not rendering medical advise. Please check with your family physician, specialist or health care professional before implementing any of the ideas expressed in these articles.

 
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