CHD kills and disables people in their most productive years and in 1999 was estimated to account for $53 billion in medical care costs and $47 billion in indirect economic costs.2 Each year there are more hospitalizations for CHD than for any broad diagnostic group, with the exceptions of births, all respiratory diseases, all digestive diseases, and all injuries.8
In the United States, an estimated 12 million people have CHD, about one-half of whom have acute MI and half have angina pectoris.2 For men, prevalence of MI is 1 percent at ages 35 to 44 years and 16 percent at age 75 and over (Fig. 1-3). In women, the prevalence is less than 1 percent at ages 35 to 44 years and 13 percent at age 75 and over.
National Health and Nutrition Examination Survey, 1988-1994, National Center for Health Statistics.) Incidence
In the United States, CHD causes about 650,000 new heart attacks each year and 450,000 recurrent attacks.2 The incidence in women lags behind that in men by 10 years for total CHD and by 20 years for more serious clinical manifestations such as MI and sudden death Tables 1-1 and 1-3). Male predominance is least striking for uncomplicated angina pectoris. The first coronary presentation for women is more likely to be angina, whereas in men it is more likely to be MI Table 1-4). In men, more angina occurs after MI than before. Only 20 percent of coronary attacks are preceded by longstanding angina; the percentage is lower if the infarction is silent or unrecognized. In premenopausal women, serious manifestations of CHD such as infarction or sudden death are relatively rare. The incidence and severity of CHD increase with age in both sexes (see Table 1-3 and Table 1-4). There seems to be a more precipitous increase for women after menopause, with CHD rates in postmenopausal women two to three times those of women the same age who remain premenopausal.21 This applies whether the menopause is natural or surgical and, in the latter case, whether or not the ovaries are removed. The sex ratio in incidence narrows progressively with advancing age.
Unrecognized MIs are common in the Framingham Study, numbering at least one in three infarctions
Fig. 1-4). Half the unrecognized infarctions are silent, and the rest are atypical so that neither the patient nor the physician entertains the possibility.22 More than half these persons eventually develop some overt clinical manifestations of CHD and hence come under medical care. Angina is less frequent in individuals with unrecognized MI than in those with recognized symptomatic MI, either before or after the infarction occurs. Despite the apparent mild nature of unrecognized MI, t risk of subsequent mortality is nearly the same as in patients with recognized infarction. Diabetic men and hypertensive persons of both sexes are particularly susceptible to silent or unrecognized MIs.
In patients who survive the acute stage of an MI, the morbidity and mortality range from 1.5 to 15 times that of the general population, depending on the person's sex and clinical outcome (Table 1-5). The rates of occurrence of reinfarction, sudden death, angina pectoris, cardiac failure, and stroke are all substantial. The relative and absolute risks of these events are as great in women as in men after MI. Within 6 years following a recognized MI, 18 percent of men and 35 percent of women have a recurrent infarction, and 27 percent of men and 14 percent of women develop angina. About 22 percent of men and 46 percent of women are disabled with cardiac failure; 8 percent of men and 11 percent of women will have a stroke. Sudden death will be experienced by 7 percent of men and 6 percent of women. The prognosis is nearly as bad, sometimes worse, following an unrecognized MI (see Table 1-5).
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