4. Increasing dosages of aspirin have more potential for side effects, most notably, stomach and intestinal ulcer formation and bleeding, as well as stroke in its rarer but more severe "bleeding" form. The risk of complications increases with age. Moreover, for those at the lowest risk of a first heart attack or stroke (less than 3 percent risk), the chance of dying from a complication of aspirin may actually exceed the benefit!
So, basically, aspirin's benefits (1, 2, and 3) need to be balanced against its risks (4). Given your situation – with known, albeit treated, coronary artery disease – 81 mg daily will definitely lower your risk of heart attack and stroke. A dose of 324 mg would decrease your risk even further, but brings with it a higher chance of bleeding complications. For the "average" patient in your category, the benefit of the higher dosage probably outweighs the risk. If, however, you have uncontrolled high blood pressure (this increases the risk of bleeding stroke) or have had a stomach or intestinal ulcer in the past (this increases the risk of another ulcer), the opposite may be true.
Fortunately, each of these additional risk factors can be modified. High blood pressure can be better controlled, and ulcer risk can be reduced by acid-blocking medications. In the end, the benefit of any ongoing use of a dosage of aspirin needs to be weighed against the possible side effects in each individual patient.
