Heart attacks and strokes are caused by tiny blood clots that form inside our arteries. Because aspirin is a mild blood thinner, it can help prevent blood clots from forming and therefore prevent these potentially life-changing events. It’s important to note that aspirin does nothing to lower blood pressure, improve cholesterol profiles, or improve blood sugar control. It also does not prevent blockages from forming. The only thing that aspirin does is mildly thin the blood, which then reduces the risk of clot formation (which is the precursor of a heart attack or stroke).
However, because it’s a blood thinner, aspirin also increases the risk of bleeding. In addition, it can irritate the lining of the stomach making bleeding inside the digestive system more likely. Most frighteningly, aspirin use increases the risk of hemorrhagic stroke. The increase in risk is tiny, but it’s not zero and a hemorrhagic stroke is certainly a devastating side effect. Aspirin may not require a prescription, but that doesn’t mean it can’t cause problems.
Patients with known cardiovascular disease (CVD) (those who have experienced a heart attack, stent, bypass surgery, non-hemorrhagic stroke, or have known peripheral vascular disease) are routinely placed on aspirin for prevention of subsequent heart or vascular events. The typical dose is 81 mg per day (“baby aspirin” dose). In these individuals, the risk of bleeding is far outweighed by the benefit of lower repeat heart event rates.
New guidelines just released by the US Preventive Services Task Force outline which individuals without known CVD might also benefit from aspirin use. These state that those over age 60 without a history of CVD should not take aspirin to prevent events while those age 40-59 without a history of CVD should make the individual choice to take it after input from their care provider.
As I see it, this latest guidance adds confusion to what we’re already doing. The current recommendations are to not place ANYONE on aspirin if they don’t have a history of CVD, regardless of age. So, the new category is really the 40 to 59-year-olds and having the option to place them on daily aspirin. For the 60+ year olds without CVD, the continued recommendation to avoid aspirin makes sense because the risk of bleeding from any blood thinner (even a mild one like aspirin) goes up with age. And the risk to benefit ratio of prophylactic aspirin in these folks becomes unacceptably high. In 40 to 59-year-olds, the decision to use aspirin would be dependent on the overall burden of risk factors. But if someone makes it to 60 without an event, what do we do then? Discontinue the aspirin – even though the risk burden hasn’t changed? And how different is the risk of bleeding in a 59-year-old compared to a 60-year-old?
Frankly, the best scenario is to not need aspirin at all! 80% of heart disease is preventable.