If you smoke, cells that line your body’s blood vessels react to the poisons in tobacco smoke almost immediately. Your heart rate and blood pressure go up. Your blood vessels grow narrower. Chemical changes caused by smoking also make blood more likely to clot. Clots can form and block blood flow to your heart.
Smoking is one cause of dangerous plaque buildup inside your arteries. Plaque clogs and narrows your arteries. This can trigger chest pain, weakness, heart attack, or stroke. Plaque can rupture and cause clots that block arteries. Completely blocked arteries can cause sudden death. Smoking is not the only cause of these problems, but it makes them much worse.