Tobacco smoke is the single most preventable cause of death in the United States. If you haven't already quit smoking, now would be an excellent time to start! Cigarette smoking and constant exposure to tobacco smoke are major risk factors for heart attack and stroke. Cigar and pipe smokers also seem to have a higher risk of death from heart disease. Scientists believe that smoking promotes heart disease in several different ways:

• It speeds the development of atherosclerosis, perhaps by damaging artery walls and allowing cholesterol to deposit

• It reduces the HDL cholesterol level

• Smoking may also trigger blood clots to form

• In those people who've previously had a heart attack, or are experiencing chest pain, smoking may disturb the heart rhythm, which can lead to sudden cardiac arrest

As soon as you quit smoking, your risk of heart disease and stroke starts to drop. Over time, your risk may be about the same as if you had never smoked at all.