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Heart Health, Explained

Aspirin: Does a Daily Dose Really Lower Cardiovascular Risk?

The U.S. Food and Drug Administration recently issued a consumer update with a reminder that taking an aspirin every day may help prevent heart attack or stroke in some people. But such a regimen is not recommended for everyone, and it can cause unwanted side effects. FDA officials said the data from major studies do not support the use of daily aspirin as a preventive medication by people who have not had a heart attack, stroke or cardiovascular problems. The consumer update was issued May 5, 2014 and publicized by NBC News.

Daily Aspirin Heart Health Q&A

Q: What was the impetus for the Food and Drug Administration to issue this reminder?

A: Years of research and many clinical trials have shown the benefit of aspirin therapy in reducing death, subsequent heart attacks, and strokes among patients who have previously experienced a heart attack or ischemic stroke. This is called secondary prevention. However, the data assessing the benefit of taking aspirin in patients who have not experienced a prior heart attack or stroke to prevent future events—primary prevention—is less robust. As such, recommendations vary regarding the appropriateness of aspirin therapy for the primary prevention of heart attack and stroke.

In 2003, the largest manufacturer of aspirin, Bayer HealthCare, petitioned the FDA for a labeling change to include an indication of aspirin for the primary prevention of heart and vascular disease in addition to the preexisting indication of aspirin for the secondary prevention of heart and vascular disease. The FDA held off its decision until the completion of several large randomized clinical trials assessing aspirin as a primary prevention therapy.

On May 5, 2014, the FDA denied the labeling change of aspirin for the primary prevention of future heart attacks or strokes. Eleven years after Bayer’s petition, the FDA reviewed all the current data and the results of six studies stating that none of the trials demonstrated a statistically significant benefit of aspirin for primary prevention. The FDA was concerned that there was an increase in bleeding events among patients receiving aspirin as compared to a placebo and decided against subjecting thousands of patients to this potential risk.

Q: Were individuals who were concerned about cardiovascular disease risks taking an aspirin a day on their own?

A: Recent publications examining aspirin use in the United States provide an overview of contemporary use of aspirin for the primary prevention of heart and vascular disease. Defining appropriate aspirin use for primary prevention as recommended by the American Heart Association (AHA), the U.S. Prevention Services Task Force, and the American Stroke Association, these studies identified that 12-19 percent of individuals who take aspirin for primary prevention at least every other day, do so either against medical advice or without a clinical indication to appropriately take aspirin. Self-administration of aspirin, particularly without a clinical indication, is not without risk. In fact, individuals on daily low-dose aspirin (81mg) are 1.5 times more likely to experience a major bleeding event as compared to those not taking aspirin.

Q: Were aspirin makers encouraging this?

A: Bayer HealthCare petitioned the FDA for a labeling change of aspirin to include treatment for the primary prevention of heart and vascular disease. The indication would have afforded Bayer the right to market their product directly to consumers for the primary prevention of heart and vascular disease. Despite the FDA rebuttal of the labeling change, Bayer continues to promote aspirin for the prevention of a first cardiovascular event, stating in their press releases that low‐dose aspirin currently is approved in more than 50 countries and that evidence‐based practice guidelines from major medical associations, including the American Heart Association, support an aspirin regimen to prevent a future cardiovascular event.

Q: Which segments of the population should consider taking aspirin daily for cardiovascular prevention? How does aspirin reduce risk?

A: Clinical guidelines support the use of aspirin for primary heart and vascular prevention among carefully identified individuals at high risk for cardiovascular disease only when the potential benefit of aspirin outweighs the associated increased risk of gastrointestinal bleeding and bleeding-related strokes. The AHA/American Stroke Association guidelines support healthcare providers recommending aspirin use for primary prevention of heart attacks and strokes to patients with a calculated 10-year risk of developing a heart attack or stroke of greater or equal to 6 percent. Prior to initiating a conversation about therapy for the primary prevention of heart attack and stroke with their healthcare providers, patients can calculate and gain insight into their 10-year risk of developing cardiovascular disease by visiting the AHA website.

Additionally, the American Diabetes Association recommends aspirin therapy for certain diabetic patients with an increased risk for the development of cardiovascular disease. It is recommended that clinicians consider aspirin as a primary prevention strategy for men with type 1 or 2 diabetes over age 50 and diabetic women over age 60 who have at least one of the following additional major heart and vascular risk factors: smoking, high blood pressure, high cholesterol, protein in the urine, or a family history of premature heart attack or stroke.

Ultimately, the decision to take aspirin for the primary prevention of heart and vascular disease is best made by a well-informed healthcare provider who assesses each individual’s risk for the development of future events and balances this benefit against each individual’s risk of complications from aspirin therapy.

Q: How does aspirin reduce risk?

A: A heart attack or ischemic stroke is a complicated process that occurs when blood carrying oxygen and other nutrients to the heart or brain is abruptly blocked by a clot. Over years, cholesterol and other fatty substances deposit into the blood vessel walls and develop into blockages called plaques, reducing the blood flow to the heart and brain and weakening the vessel wall. When a plaque ruptures in a blood vessel supplying blood to the heart, blood components called platelets form a clot that stops blood flow to the heart muscle and causes a heart attack. The same type of plaque rupture in vessels supplying blood to brain tissues results in a stroke.

Aspirin reduces the risk of future heart attacks and strokes by interfering with the activation of platelets, decreasing the risk of a blood clot stopping blood flow to heart or brain tissue. However, aspirin blocking of platelet activation also decreases the body’s natural ability to stop bleeding.

Q: Are the cardiovascular health risks and benefits of taking aspirin daily different for women compared to men?

A: Despite improved public awareness of differences in cardiovascular disease in men and women, the absolute number of deaths each year among women continues to exceed that of men and has since 1984. Reasons include women having a difference in response to medical therapy as compared to men. Gender differences in response to aspirin therapy for primary prevention have been documented and are significant. Aspirin therapy provided to men as part of a primary prevention treatment strategy reduces heart attacks by 32 percent. The therapy showed no reduced risk of heart attacks for women. However, women gain a 17 percent reduction in the development of future strokes, an effect not found in men.

The AHA guidelines accurately account for these gender differences by recommending aspirin as a primary prevention therapy for the risk reduction of future heart attacks in men and for the risk reduction of future ischemic strokes in women. Recommendations are for aspirin utilization as long as the potential benefits outweigh the potential risks of major bleeding events, which occur with equal frequency among both men and women.

Q: Why should people who have not had a heart attack or stroke avoid daily aspirin?

A: Overall, the risk of developing a heart attack or stroke for individual patients who have not previously experienced either is generally low. However the risk of heart and vascular disease increases with age and certain risk factors. If the benefits of aspirin were without side effects —primarily gastrointestinal bleeding (1.3 fold increased risk) and hemorrhagic stroke (1.5 fold increased risk) — it would seem reasonable for all aging individuals to consider aspirin therapy to prevent a future heart attack or stroke. However, the balance of the potential benefit to the significant potential risk associated with aspirin mandates a careful, shared decision between you and your healthcare provider before taking daily aspirin for the primary prevention of cardiovascular disease.

Q: What about people who have a family history of heart disease or evidence of arterial disease?

A: Advancements in genetic analysis have confirmed what physicians and patients have long thought—that individuals with a family member who have a heart attack or stroke at a young age are at a higher risk for the development of cardiovascular disease themselves. In fact, an individual with a parent or sibling who experienced a heart attack or stroke at a young age (men under 55 and women under 65) is at a 33 percent increased risk for a heart attack or stroke. Although a family history of early cardiovascular disease is a risk factor individuals cannot modify, risk factors such as smoking history, high blood pressure, high cholesterol, uncontrolled diabetes, obesity and physical inactivity are modifiable and if treated appropriately can decrease one’s risk for the development of future heart attack or stroke. Therefore all patients should identify and address all modifiable risk factors as part of a comprehensive, primary prevention strategy. Calculating one’s risk for the development of cardiovascular disease based on the presence of risk factors and age is complicated and may result in the recommendation of aspirin therapy by a physician. The balance between the benefit of aspirin therapy with the potential bleeding risk is even more complicated and best addressed during a conversation with a well-informed healthcare professional.

Q: There seems to be widespread interest in the topic of aspirin for primary prevention of cardiovascular disease. Are there ongoing clinical studies to further investigate this topic?

A: To date, published studies of aspirin therapy for the primary prevention of heart and vascular disease have shown inconsistent findings and are mostly looking at low risk patients. The cardiovascular community and the FDA are awaiting the results of five ongoing, well-designed studies assessing aspirin therapy for the primary prevention of cardiovascular disease among higher risk patients. The studies include the following: ARRIVE (Aspirin to Reduce Risk of Initial Vascular Events) is a study of 12,000 patients with several risk factors for heart and vascular disease over five years; ASCEND (A Study of Cardiovascular Events in Diabetes) is a 10,000-patient study of aspirin use in individuals with diabetes; ASPREE (Aspirin in Reducing Events in the Elderly) is enrolling 15,000 elderly patients; ACCEPT-D (Aspirin and Simvastatin Combination for Cardiovascular Events Prevention Trial in Diabetes) encompassing 5,000 patients with diabetes. It is anticipated that these studies of higher risk patients, with a sound design, will allow the FDA to unequivocally decide on the role of aspirin therapy for the primary prevention of heart and vascular disease.

HEALTH NEWS IN PERSPECTIVE

Answers to your questions on timely topics in cardiac care to help make sense of research reports in the media. The series includes questions on your heart and the effect of medications, exercise, diet, and hormones.

Team Specialist

Michael Tempelhof, MSc, MD, FACC Interventional Cardiology OhioHealth Healthcare System, Columbus, Ohio

Q&A Editor

Teresa Caulin-Glaser, MD, FACC, FAACVPR System Vice President, Heart & Vascular Services OhioHealth Healthcare System, Columbus, Ohio

Heart Health Explained is a collaboration of Women’s Health Research at Yale and the OhioHealth Healthcare System, a nationally recognized not-for-profit organization with providers across 46 counties, offering a holistic approach to prevention, treatment and rehabilitation of heart disease. OhioHealth is staffed by physicians, psychologists, nutritionists and nurses who answer the questions of the moment on heart and vascular health.

The information provided here may help you make more informed choices. However, it is not a substitute for an individualized medical opinion or diagnosis, and everyone should always consult with their personal physicians to make decisions about their condition or treatment.