(FORTUNE Magazine) – The symptoms of a heart attack aren't necessarily obvious. People talk of chest pain, but it's usually pressure or a squeezing sensation. This is called angina, and it occurs when blood flow in one of the arteries that supply the heart is decreased because of a buildup of plaque. If the artery becomes blocked, a heart attack usually follows. Angina may radiate down the left arm and occasionally up into the jaw. It should always be evaluated by a physician.

One common mistake is not seeking immediate medical attention. Believing heart attacks are for men, women frequently ignore the symptoms--which can also include shortness of breath, sweating, lightheadedness, nausea, and fainting. But heart disease is the leading cause of death in women too. In fact, half of all people who experience symptoms wait at least two hours before seeking treatment. That is tragic because most deaths occur during the first hour--the result of an abnormal heart rhythm known as an arrhythmia. CPR may buy you some time, as may the defibrillators carried by most ambulance crews. Clot-busting medications or angioplasty can open a blocked artery. But if more than a few hours pass, it's usually too late.

If you experience any symptoms, call 911. Don't drive yourself to the hospital. Chew an aspirin, lie down, and rest. Taking an aspirin right after a heart attack can reduce the risk of death about 25%.

Then what? Nowadays people are often discharged from the hospital soon after an uncomplicated attack. Serious lifestyle changes need to be made, however. The majority of patients will be encouraged to participate in a cardiac rehab program, including exercise at an appropriate level. The benefits of exercise far outweigh any risk of creating more heart problems.

Next: a diet low in animal products containing cholesterol and saturated fat and high in fiber-rich vegetables, fruits, and other plant products. The monounsaturated fats in olive oil, canola oil, and nuts are good, as are the omega-3 fatty acids in fish. One or two drinks a day may help reduce risk, and excess weight should be shed. Risk factors--diabetes, high blood pressure--should be tightly controlled. Tobacco, even deadlier after a heart attack, is out.

As for medications, an aspirin a day is usually a good idea. Most survivors should also probably be on one of the statin drugs, which lower cholesterol and decrease the risk of more attacks. Beta blockers or angiotensin-converting-enzyme (ACE) inhibitors may help the heart function better and lower blood pressure.

Quality of life after an attack depends on how much of the heart has been damaged, how well it functions, and how much blockage is still present. Many people whose heart attacks were caught early can go back to the activities they previously enjoyed. Some people actually view an attack as positive. The changes it forces them to make will help them feel better and live longer.

For more information on this topic: Go to mayoclinic.com. Mayo Clinic offers Executive Health programs at Mayo Clinics in Jacksonville, Fla.; Rochester, Minn.; and Scottsdale, Ariz.