Aspirin’s Role in Heart Disease

Life Extension has repeatedly alerted its members to the lethal dangers of endothelial dysfunction, the key underlying factor in the progression of atherosclerosis, or hardening of the arteries. (See “Why Our Arteries Become Clogged as We Age,” Life Extension, October 2005.)

Endothelial dysfunction occurs when the blood vessel linings can no longer dilate in response to demands for increased blood flow. Emerging studies indicate that aspirin may protect against heart disease in part by improving endothelial function. In a study of 14 patients with coronary atherosclerosis, aspirin helped improve the ability of blood vessels to dilate, indicating an improvement in endothelial function. This led the study authors to suggest that aspirin therapy could help improve endothelial dysfunction and inhibit the advance of atherosclerosis.28

The heart depends on its coronary arteries for the oxygen supply that fuels this most vital of organs. Coronary heart disease occurs when normal blood flow through the arteries that feed the heart is slowed or interrupted by factors such as blood clots or plaque.

Preventing clots is another way that aspirin helps prevent heart attacks. By irreversibly blocking production of the clot-promoting biochemicals known as thromboxanes, aspirin prevents platelets in the blood from latching on to each other and forming a clot. A platelet has a life span of 10 days, and aspirin permanently impairs the platelet’s clotting ability.29 Aspirin helps blood flow more smoothly past any plaque that is narrowing an artery, and if a plaque ruptures, aspirin will reduce the likelihood of a clot clinging to it.30

Aspirin can also help prevent heart disease through its anti-inflammatory action. Inflammation participates in many disease processes in the body, including plaque accumulation in the arteries.31 The growth of plaque can obstruct blood flow through the arteries. If a plaque ruptures due to inflammation, it can trigger a heart attack.

A 2003 meta-analysis examined aspirin’s effects on primary heart-attack prevention (that is, the prevention of first heart attacks). In more than 55,000 men and women, aspirin use was associated with a 32% reduction in the risk of having a first heart attack, and with a 15% reduction in the risk of all major vascular events.32

A study presented at the 2005 meeting of the American Heart Association reported on the lifesaving benefits of aspirin therapy. This study examined nearly 9,000 women with stable heart disease, ranging in age from 50 to 79. During more than six years of follow-up, women taking aspirin were 25% less likely to die from heart disease and 17% less likely to die from any cause. Some women took 81 mg of aspirin daily, while others took 325 mg. The study authors stated that the two doses appeared to be similarly effective, but that higher doses of aspirin are associated with a greater risk of certain side effects, such as stomach bleeding.33

A meta-analysis published in 2006 examined the effects of aspirin therapy in preventing cardiovascular events in women and men. Examining data from more than 50,000 women, investigators determined that aspirin therapy was associated with a significant 12% reduction in cardiovascular events in women. Among more than 44,000 men, aspirin therapy produced a significant 14% reduction in all cardiovascular events and an even more impressive 32% reduction in heart attacks.34

According to the US Preventive Services Task Force, aspirin’s proven benefits are reason enough for people to start using it if they have at least a 6% chance of developing coronary heart disease in the next 10 years. By contrast, the American Heart Association recommends aspirin for people whose 10-year risk of developing coronary heart disease is 10% or higher, as long they have no medical contraindications for taking the drug. A doctor can help you calculate your cardiovascular risk based on factors such as tobacco use, cholesterol, and blood pressure.35,36 You can also assess your cardiovascular risk by using online risk factor calculators available at the American Heart Association website.

Life Extension strongly recommends that people who have already had a heart attack (or other episode of heart disease) discuss aspirin therapy with their doctor as part of a strategy to prevent future problems. Life Extension also suggests that people with no previous history of cardiovascular disease—but who are nevertheless at high risk for heart disease—strongly consider aspirin therapy in consultation with their personal physician. The recommended dose for preventing heart-related problems is 81-325 mg daily. Speak with your doctor about your personal needs before beginning aspirin therapy.

Aspirin and Stroke: Risk vs. Benefit

The brain requires a constant supply of oxygen from freshly flowing blood to convert glucose into energy.38 During a stroke, blood flow to part of the brain is cut off, and the damage from this interruption can cause death, disability, impaired speech, and myriad other adverse effects.

The most common type of stroke—known as ischemic stroke—occurs when an artery becomes blocked, limiting blood supply to areas of the brain. This type of stroke accounts for about 80% of stroke cases. The other 20% or so are cases of hemorrhagic stroke, which is caused by a blood vessel rupturing and spilling blood into the brain. Aspirin plays vastly different roles in these two types of stroke.

Aspirin helps to decrease the risk of ischemic stroke by keeping blood platelets from sticking together to form a clot, so that blood continues to flow past any narrowed spots in the arteries that feed the brain. However, some studies suggest that taking aspirin may cause a slight increase in a person’s chance of having a hemorrhagic stroke. The US Preventive Services Task Force estimates that if 1,000 people took aspirin for five years, as many as 2 would suffer a hemorrhagic stroke.39

A study published in March 2005 examined aspirin’s effects on women. Nearly 40,000 middle-aged and older women were assigned to take either placebo or 100 mg of aspirin every other day for 10 years. Women who took aspirin had a notable 24% reduced risk of ischemic stroke. In this study, however, aspirin use was associated with slightly higher risks of gastrointestinal bleeding and hemorrhagic stroke.40

Another study reported in late 2005 examined the effects of aspirin therapy in more than 50,000 women who did not have coronary heart disease. Aspirin use was associated with a 17% reduction in the risk of suffering a stroke, and a 24% reduction in the risk of ischemic stroke. In this study, aspirin use did not appear to increase the risk of hemorrhagic stroke.33

Once your risk factors for stroke—like hypertension, high cholesterol, diabetes, or smoking—start adding up, you and your doctor need to discuss aspirin therapy, particularly as you grow older and advance into age groups that bear a heavier stroke risk. If you have suffered a hemorrhagic stroke, aspirin should not be used. In general, 81-325 mg of aspirin daily is used as part of a stroke-prevention program.

Conclusion

Life Extension was at the forefront in advocating aspirin use to decrease cardiovascular risk, long before the mainstream medical community finally recognized the lifesaving benefits of aspirin.

Exciting new research findings support a disease-preventive benefit for aspirin in other potentially lethal conditions such as skin cancer, colon cancer, and Alzheimer's. Life Extension will continue to monitor ongoing research on aspirin and share with members important findings that are often overlooked by the mainstream medical establishment.

An overlooked staple of the medicine cabinet, aspirin continues to prove its value as one of our most powerful allies in fighting the deadly diseases that accompany aging.

Caution: Individuals with allergies to aspirin or other salicylates should not use aspirin. People with a history of bleeding disorders, hemorrhagic stroke, asthma, or ulcers should speak with a doctor before using aspirin. Consult a physician before using aspirin in combination with over-the-counter or prescription medications. Children and teenagers with symptoms of flu or chicken pox should not take aspirin.