We think aspirin helps keep the arteries free of clots and prevents heart attacks in two ways. First, aspirin decreases inflammation in the arteries. Second, it inhibits the prostaglandin system, an enzyme system that causes platelets to stick together (clot). Aspirin also seems to prevent aging of the blood vessels in other ways. For example, aspirin may help the body build auxiliary blood vessels, so that if and when clots do break off, enlarge, and clog blood vessels, the body has alternate routes for blood flow around the clogged vessel. Aspirin may help decrease inflammation in the walls of the blood vessels that are caused by infections elsewhere in the body (or those that are caused when particles such as homocysteine attack blood vessel walls), and thus prevents turbulent blood flow that can lead to fatty buildup.
More Answers from Michael Roizen, MD