Why does smoking increase the risk of heart attack and stroke?

Smoking significantly increases the risk of heart attack and stroke by damaging the circulatory system through several mechanisms.12

• Vascular Damage: Chemicals in tobacco smoke injure the endothelium, the inner lining of blood vessels. This damage allows fat and debris to accumulate, leading to atherosclerosis—the hardening and narrowing of arteries—which restricts blood flow.13
• Blood Composition: Smoking makes blood thicker and stickier, increasing the likelihood of dangerous clots that can block blood supply to the heart or brain.13
• Reduced Oxygenation: Carbon monoxide in smoke binds to hemoglobin, reducing the blood's capacity to carry oxygen. This forces the heart to work harder to supply the body.12
• Increased Strain: Nicotine constricts blood vessels, raising blood pressure and heart rate, which places additional, chronic stress on the cardiovascular system.1

These combined effects create a high-risk environment for myocardial infarction and other life-threatening cardiovascular events.23