What is a heart attack?

Heart attacks (also called coronary attacks) result from coronary heart disease -- disease of the blood vessels that feed the heart muscle. Coronary artery disease and ischemic (is-KEM'ik) heart disease are other names for coronary heart disease.

What causes a heart attack?

A heart attack occurs when the blood supply to part of the heart muscle itself -- the myocardium (mi"o-KAR'de-um) -- is severely reduced or stopped. The medical term for heart attack is myocardial infarction (mi"o-KAR'de-al in-FARK'shun). The reduction or stoppage happens when one or more of the coronary arteries supplying blood to the heart muscle is blocked. This is usually caused by the buildup of plaque (deposits of fat-like substances) due to atherosclerosis (ath"er-o-skleh-RO'sis). The plaque can eventually burst, tear or rupture, creating a "snag" where a blood clot forms and blocks the artery. This leads to a heart attack. A heart attack is also sometimes called a coronary thrombosis (throm-BO'sis) or coronary occlusion (o-KLOO'zhun).

If the blood supply is cut off for more than a few minutes, muscle cells suffer permanent injury and die. This can kill or disable someone, depending on how much heart muscle is damaged.

Sometimes a coronary artery temporarily contracts or goes into spasm. When this happens the artery narrows and blood flow to part of the heart muscle decreases or stops. We're not sure what causes a spasm. But a spasm can occur in normal-appearing blood vessels as well as vessels partly blocked by atherosclerosis. A severe spasm can cause a heart attack.

How Can I Reduce My Chances of a Heart Attack?

The American Heart Association has identified six key risk factors people can treat or modify to reduce their risk of a heart attack. Addressing these risk factors can have immediate benefits to your overall health and well being.

Extensive clinical and statistical studies have identified several factors that increase the risk of coronary heart disease and heart attack. Major risk factors are those that research has shown significantly increase the risk of heart and blood vessel (cardiovascular) disease. There are other factors associated with increased risk of cardiovascular disease, but their significance and prevalence haven't yet been precisely determined. These are called contributing risk factors.

The American Heart Association has identified several risk factors. Some of them can be modified, treated or controlled, and some can't. The more risk factors you have, the greater your chance of developing coronary heart disease. Also, the greater the level of each risk factor, the greater the risk. For example, a person with a total cholesterol of 300 mg/dL has a greater risk than someone with a total cholesterol of 240 mg/dL, even though everyone with a total cholesterol greater than 240 is considered high-risk.

What are the major risk factors that can't be changed?

Increasing age ? About four out of five people who die of coronary heart disease are 65 or older. At older ages, women who have heart attacks are more likely than men are to die from them within a few weeks.

Male sex (gender) ? Men have a greater risk of heart attack than women do, and they have attacks earlier in life. Even after menopause, when women's death rate from heart disease increases, it's not as great as men's.

Heredity (including Race) ? Children of parents with heart disease are more likely to develop it themselves. African Americans have more severe high blood pressure than Caucasians and a higher risk of heart disease. Heart disease risk is also higher among Mexican Americans, American Indians, native Hawaiians and some Asian Americans. This is partly due to higher rates of obesity and diabetes. Most people with a strong family history of heart disease have one or more other risk factors. Just as you can't control your age, sex and race, you can't control your family history. It's even more important to treat and control any other risk factors you have.

What are the major risk factors you can modify, treat or control by changing your lifestyle or taking medicine?

Tobacco smoke ? Smokers' risk of heart attack is more than twice that of nonsmokers. Cigarette smoking is the biggest risk factor for sudden cardiac death. Smokers have two to four times the risk of nonsmokers. Smokers who have a heart attack also are more likely to die and die suddenly (within an hour). Cigarette smoking also acts with other risk factors to greatly increase the risk for coronary heart disease. People who smoke cigars or pipes seem to have a higher risk of death from coronary heart disease (and possibly stroke) but their risk isn't as great as cigarette smokers'. Constant exposure to other people's smoke increases the risk of heart disease even for nonsmokers.

High blood cholesterol ? As blood cholesterol rises, so does risk of coronary heart disease.. When other risk factors (such as high blood pressure and tobacco smoke) are present, this risk increases even more. A person's cholesterol level is also affected by age, sex, heredity and diet.

High blood pressure ? High blood pressure increases the heart's workload, causing the heart to enlarge and weaken. It also increases your risk of stroke, heart attack, kidney failure and congestive heart failure. When high blood pressure exists with obesity, smoking, high blood cholesterol levels or diabetes, the risk of heart attack or stroke increases several times.

Physical inactivity ? An inactive lifestyle is a risk factor for coronary heart disease. Regular, moderate-to-vigorous physical activity helps prevent heart and blood vessel disease. The more vigorous the activity, the greater your benefits. However, even moderate-intensity activities help if done regularly and long term. Exercise can help control blood cholesterol, diabetes and obesity, as well as help lower blood pressure in some people.

Obesity and overweight ? People who have excess body fat ? especially if a lot of it's in the waist ? are more likely to develop heart disease and stroke even if they have no other risk factors. Excess weight increases the strain on the heart. It also raises blood pressure and blood cholesterol and triglyceride (tri-GLIS'er-íd) levels, and lowers HDL ("good") cholesterol levels. It can also make diabetes more likely to develop. Many obese and overweight people may have difficulty losing weight. But by losing 10 to 20 pounds, you can help lower your heart disease risk.

Diabetes mellitus (di"ah-BE'teez or di"ah-BE'tis meh-LI'tis) ? Diabetes seriously increases your risk of developing cardiovascular disease. Even when glucose levels are under control, diabetes greatly increases the risk of heart disease and stroke. About two-thirds of people with diabetes die of some form of heart or blood vessel disease. If you have diabetes, it's extremely important to work with your healthcare provider to manage it and control any other risk factors you can.

What other factors contribute to heart disease risk?

• Individual response to stress may be a contributing factor. Some scientists have noted a relationship between coronary heart disease risk and stress in a person's life, their health behaviors and socioeconomic status. These factors may affect established risk factors. For example, people under stress may overeat, start smoking or smoke more than they otherwise would.

• Sex hormones seem to play a role in heart disease. It's well known that men have more heart attacks than women do before women reach the age of menopause. Several population studies show that the loss of natural estrogen as women age may contribute to a higher risk of heart disease after menopause. If menopause is caused by surgery to remove the uterus and ovaries, the risk of heart attack rises sharply. If menopause occurs naturally, the risk rises more slowly.

• Hormones also affect blood cholesterol. Female hormones tend to raise HDL ("good") cholesterol and lower total blood cholesterol. Male hormones do the opposite.

• If you've had a natural or surgical menopause, you may be considering estrogen replacement therapy (ERT) or hormone replacement therapy (HRT). ERT and HRT may increase your risk of some diseases and health conditions. Your healthcare provider can give you more information and help you make the best choice.

• The early forms of birth control pills, with higher doses of estrogen and progestin (pro-JES'tin), increased a woman's risk of heart disease and stroke. That's especially true for older women who smoked. Newer, lower-dose oral contraceptives carry a much lower risk of cardiovascular disease, except for women who smoke or have high blood pressure.

• If a woman taking oral contraceptives has other risk factors (and especially if she smokes), her risk of developing blood clots and having a heart attack goes up. It rises even more after age 35. If you take birth control pills, get your blood pressure, triglyceride and glucose levels checked yearly.

• Drinking too much alcohol can raise blood pressure, cause heart failure and lead to stroke. It can contribute to high triglycerides, cancer and other diseases, and produce irregular heartbeats. It contributes to obesity, alcoholism, suicide and accidents.

• The risk of heart disease in people who drink moderate amounts of alcohol (an average of one drink for women or two drinks for men per day) is lower than in nondrinkers. One drink is defined as 1-1/2 fluid ounces (fl oz) of 80-proof spirits (such as bourbon, Scotch, vodka, gin, etc.), 1 fl oz of 100-proof spirits, 4 fl oz of wine, or 12 fl oz of beer. It's not recommended that nondrinkers start using alcohol or that drinkers increase the amount they drink.