Gender
Coronary artery disease is much more common in older people
and in males. But slowly, women are catching up, and deaths from heart
disease are evenly split between men and women. A number of studies
report higher mortality rates from heart attacks in women. Although
women tend to be older and sicker when they are first treated for a
heart attack, a number of studies have indicated that these factors do
not entirely explain the differences. Evidence has suggested that women,
particularly the elderly, are less aggressively treated than men for all
phases of heart disease, including angina attacks and heart attack. In
one study women were given fewer beta-blockers, anti-clotting
medications, and surgical procedures than men and were treated an
average of 14 minutes later with time-critical thrombolytic treatments.
It appears to be younger women, however, who are at greater risk of
death from a heart attack than men their own age. One possible
explanation for the later treatment and higher death rate in younger
women is the possible failure to recognize symptoms in this population,
particularly in younger women.
Ethnicity
In a 1998 analysis, the mortality rates from coronary artery
disease declined between 1987 and 1994 in both Caucasians and African
Americans; however it is decreasing significantly in Caucasians but not
in African Americans. African American women still face the highest risk
for death from heart disease, and their rate of heart attacks are
increasing. Although socioeconomic factors, such as poor diet, higher
stress levels, and lack of access to health care certainly play
significant roles in these differences, biologic factors may be involved
in certain people. Some African Americans with coronary artery disease
appear to have a genetic trait that increases the danger of
triglycerides, a particular risk factor in women. One study found that
African Americans produce less nitric oxide in response to stress; this
substance is critical for opening blood vessels and increasing blood
flow. Native Americans, particularly those in North and South Dakota,
also face a much higher risk for heart disease than whites. Hispanics
have a lower risk for heart disease than all these groups.
Smoking
Smoking contributes to the development of atherosclerosis by
lowering HDL levels and causing deterioration of elastic properties in
the blood vessels which reduces blood flow. Cigarette smoking is
directly responsible for nearly 20% of all deaths from heart disease,
and smokers are 2.5 times more likely to suffer heart attacks than are
nonsmokers. They are also more at risk for death from a heart attack.
Women who smoke have an even higher risk than male smokers. Secondhand
smoke also increases the risk of heart attack in non-smokers. One study
showed that those living with heavy smokers have a four-fold higher risk
of heart attack. Quitting usually reduces the risk for a heart attack,
although evidence suggests that at least some of the smoke-induced
damage in the arteries may be irreversible.
Cholesterol
and Lipids
Total cholesterol levels should be 200 mg/dl or less. In
healthy people LDL cholesterol levels should be 160 mg/dl or below and
in people with coronary artery disease LDL should fall below 100 mg/dl.
The lower the better. HDL levels should be well above 35 mg/dl. (An HDL
level above 60 may offer enough protection to cancel out a risk factor.)
Triglyceride levels should be under 200 mg/dl, although some experts
recommend that they be under 100. Elevated levels of other lipids,
including lipoprotein (a) and apolipoprotein A-1 and B are also now
thought to be important indicators of heart risk. Apolipoprotein B may
actually turn out to be a very accurate indicator of heart disease risk
in women.
High
Blood Pressure
High blood pressure, or hypertension, has long been a proven
cause of coronary artery disease. Blood pressure that measures above
140/90 in the doctor's office indicates hypertension, although experts
now recommend that anyone with 135/99 should also monitor blood pressure
at home.
Effects
of Exercise and Sedentary Lifestyles
People who are sedentary are almost twice as likely to
suffer heart attacks as are people who exercise regularly. Regular
moderate aerobic exercise, such as brisk walking, lowers the heart rate
and blood pressure, improves cholesterol, lowers blood sugar levels,
fights blood clots, and reduces stress in both men and women. The
brisker and longer the walks the more protection exercise offers for
both men and women who are able to engage in more vigorous exercise.
Healthy people can exercise without supervision. Even elderly people
with unstable angina or who had a previous heart attack can benefit from
a structured aerobics program. It should be noted, however, that sudden
strenuous exercise (such as snow shoveling and mowing lawns) puts people
with heart disease at risk for angina and heart attack. Activities that
involve raising the arms above the head may also be risky. Patients with
angina should never exercise shortly after eating. People with risk
factors for heart disease should seek medical clearance and a detailed
exercise prescription. And all people, including healthy individuals,
should listen carefully to their bodies for signs of distress as they
exercise.
Diabetes
and Insulin Resistance
Cardiovascular disease is two to four times more prevalent
in people with diabetes. Common conditions occurring in diabetes, such
as obesity and high blood pressure, partially account for this high
risk. Insulin resistance, which occurs in people with diabetes and some
nondiabetics, appears to be an independent risk factor for heart
disease. According to a new study this risk is especially significant in
elderly men. This condition occurs when insulin levels are normal to
high but the body is unable to use the insulin to regulate metabolism of
blood sugar and to store it for energy. In such cases, the body
compensates by increasing insulin levels (hyperinsulinemia), which in
turn increases triglyceride levels and reduces HDL cholesterol.
Obesity
Obesity is related to hypertension, diabetes, abnormal
cholesterol levels, and lack of exercise, all conditions contributing to
heart attack risk. Abdominal obesity (the "beer belly") poses
a particular risk. Obesity in children is a greater risk for future
heart trouble than a family history of heart disease. People who are
overweight in middle age may still not completely reduce their risk for
coronary artery disease later in life, even if they lose excess weight.
Homocysteine
Abnormally high blood levels of the amino acid homocysteine
are strongly linked to an increased risk of coronary artery disease and
stroke. Homocysteine may harm the lining of the arteries and contribute
to blood clotting. Excessive levels occur with deficiencies of vitamins
B6, B12, and folic acid. Some experts believe that high levels of
homocysteine are only indicators, not causes, of heart disease, although
some studies have suggested that taking daily supplements of vitamins B6
(3 mg) and folic acid (at least 400 micrograms) can reduce its risk.
(Cold cereals are now fortified with folic acid.)
Psychologic
Factors
Stress.
Mental stress is as important a trigger for angina as physical stress,
and studies indicate that in people with heart disease it poses a higher
risk for serious cardiac events, such as heart attacks, and even death
from such events. In one study middle-aged women who were hostile, self
conscious in public, and suppressed anger had an increased risk of
developing atherosclerosis. And another recent one reported that angry
young men were at higher risk for heart disease in later life.
Depression.
In one 30-year study, men who were clinically depressed had a greater
risk for heart disease and heart attack than men who were not depressed;
this increased risk lasted for decades. Although some studies have
failed to show an association between depression and heart disease in
women, a 1998 study reported that depression is a significant risk
factor for death in older women, particularly from heart disease, and
the risk is equal to that from smoking or high blood pressure.
Depression may even impair a patient's response to medication for heart
disease. The more severe the depression, the more dangerous to the
health, although some studies have indicated that even mild depression,
including feelings of hopelessness, experienced over many years may harm
the hearts in people with no early signs of heart disease.
Genetic
Factors
Research indicates that genetics are involved in the
development of atherosclerosis. One important factor is apolipoprotein E
(ApoE), which appears to affect cholesterol levels. One genetic variant
called apoE4 is particularly associated with heart disease and a 1999
study suggests that it may be a significant risk factor for coronary
artery disease in early middle age. (This variant also increases the
risk for Alzheimer's disease.)
