Smoking or using tobacco of any kind is one of the most significant risk factors for developing heart disease. Chemicals in tobacco can damage your heart and blood vessels, leading to narrowing of the arteries (atherosclerosis). Atherosclerosis can ultimately lead to a heart attack.

Carbon monoxide in cigarette smoke replaces some of the oxygen in your blood. This increases your blood pressure and heart rate by forcing your heart to work harder to supply enough oxygen. Women who smoke and take birth control pills are at greater risk of having a heart attack or stroke than are those who don't do either because both smoking and taking birth control pills increase the risk of blood clots.

"Coronary heart disease (CHD) occurs when your coronary arteries become clogged with fatty material called plaque or atheroma. This process is called atherosclerosis."

When it comes to heart disease prevention, no amount of smoking is safe. But, the more you smoke, the greater your risk.

Smokeless tobacco and low-tar and low-nicotine cigarettes also are risky, as is exposure to secondhand smoke. Even so-called "social smoking" — smoking only while at a bar or restaurant with friends — is dangerous and increases the risk of heart disease.

The good news, though, is that when you quit smoking, your risk of heart disease drops almost to that of a nonsmoker in about five years. And no matter how long or how much you smoked, you'll start reaping rewards as soon as you quit.