In the United States, almost one-third of all deaths from coronary heart disease each year are related to smoking.¹ Researchers don't know exactly how smoking harms your heart. But they do know that nicotine and other byproducts of smoking damage the lining of your arteries. And these byproducts also make blood stickier and more likely to clot. If you get blood clots in the arteries that supply your heart with blood (your coronary arteries) they can stop blood from reaching your heart and cause heart muscle to die.

If you have other risk factors for a heart attack or have already been diagnosed with heart disease, smoking is particularly dangerous. Smokers who have heart attacks are more likely to die than nonsmokers who have heart attacks. The more you smoke, the higher your risk. And inhaling other people's tobacco smoke at home or at work increases your risk of getting heart disease by about 30 percent.²

If you quit smoking you can reduce your risk of getting heart disease or having a heart attack. You can get help with quitting. Treatments that work include nicotine replacement gum or a skin patch, a drug called bupropion (Zyban) and counseling. (To learn more, see our section on Stopping smoking.) Talk to your doctor if you need help quitting.

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.