Aspirin earns its keep after a heart attack, but before one it often doesn’t

Key takeaways

• In pooled trials, daily aspirin prevented about 15 heart attacks, strokes or vascular deaths per 1,000 people a year after a first event, but fewer than 1 per 1,000 in people without heart disease, by our math⁴.
• The U.S. Preventive Services Task Force advises against starting aspirin for prevention at 60 or older; in one trial of 19,114 healthy older adults, aspirin raised major bleeding without clearly lowering heart events¹².
• A 2026 cholesterol guideline from the American College of Cardiology and the American Heart Association matches treatment to your risk before a first event, then sets an LDL goal below 55 for most people after one⁶⁷.
• Drugs that lower breast cancer risk prevented 7 to 16 cancers per 1,000 higher-risk women over five years, and the Task Force advises against them for women not at increased risk¹⁰.
• If you already take aspirin or a statin, talk with your clinician before changing anything; the Task Force says not to stop aspirin on your own¹.

In 2018, researchers in Australia and the United States reported on 19,114 healthy older adults. Half took a 100-milligram aspirin every day. Half took a dummy pill. They were followed for a median of 4.7 years².

The aspirin did not clearly lower heart disease or stroke. It did raise major bleeding, from 6.2 to 8.6 cases per 1,000 people each year².

Four years later, the U.S. Preventive Services Task Force, an independent panel that grades preventive care, told clinicians not to start daily aspirin for prevention in people 60 and older¹.

Yet the American College of Cardiology still recommends low-dose aspirin for people who have already had a heart attack or stroke⁵. Same pill, same dose. The difference is what has already happened to you.

Where you stand on the prevention ladder changes who benefits, by how much, and how much harm is worth risking.

“Secondary prevention” means two different things

Our article on prevention versus treatment laid out the levels public health uses. In short, primary prevention stops a disease before it starts. Secondary prevention catches it early, often through screening. Tertiary prevention limits the damage once disease is present, and quaternary prevention protects people from care they don’t need¹¹.

Heart doctors use one of these words differently. In cardiology, “secondary prevention” means preventing another heart attack or stroke in someone who has already had one, or who has known artery disease⁴⁵. Public health would file much of that under tertiary prevention.

The mix-up matters for headlines. “Aspirin fails for prevention” usually means it fails in people without heart disease, and says little about people who have it. So this article mostly says “before a first event” and “after an event.”

Aspirin shows how much the level changes the math

The clearest evidence comes from the Antithrombotic Trialists’ Collaboration, which pooled individual patients’ data from aspirin trials. In 2009, it published an analysis in The Lancet of 6 trials with about 95,000 people who had no heart disease, and 16 trials with about 17,000 people who did⁴.

In people without heart disease, serious vascular events (heart attacks, strokes and vascular deaths) struck 0.57% of people a year without aspirin and 0.51% with it⁴. Major bleeding outside the brain rose from 0.07% to 0.10% a year⁴.

In people who had already had a heart attack or stroke, the same serious events struck 8.2% of people a year without aspirin and 6.7% with it⁴.

Here are those results as people, by our math.

Per 1,000 people, per year	Serious events without aspirin	With aspirin	Events prevented	Extra major bleeds
No known heart disease (6 trials)4	About 5.7	About 5.1	About 0.6	About 0.3
After a heart attack or stroke (16 trials)4	About 82	About 67	About 15	Not given in the summary we read
Healthy older adults, mostly 70 and up, ASPREE trial2	About 11.3	About 10.7	No clear difference	About 2.4

ASPREE counted heart failure hospitalizations as heart events, so its row isn’t a perfect match³. Still, the pattern is plain: after a first event, aspirin prevented about 25 times as many events per 1,000 people as before one, by our math.

Part of that gap comes from aspirin working a bit better in relative terms after an event: a cut of about 18%, by our math, versus 12%⁴. Most of it comes from starting risk, which was about 14 times higher. The same percentage cut from a bigger number spares far more people.

Bleeding doesn’t follow that pattern, because a low heart risk doesn’t mean a low bleeding risk. In people without heart disease, the extra bleeding can cancel the small gain, and the trialists called aspirin’s net value there uncertain⁴.

Why the aspirin advice for healthy older adults reversed

ASPREE tested aspirin in older people with no heart disease, dementia or disability². Its main question was whether aspirin kept people alive and free of dementia and disability. It didn’t: 21.5 events per 1,000 people a year on aspirin, 21.2 on placebo³.

The extra bleeding came mainly from the brain and the upper gut³. Deaths were also a little higher on aspirin, 5.9% versus 5.2%, with more cancer deaths (3.1% versus 2.3%). The American College of Cardiology’s trial summary urged caution on that finding, because earlier trials hadn’t seen it³.

By our math, ASPREE’s bleeding rates work out to about 11 extra major bleeds for every 1,000 people over the trial’s 4.7 years².

The Task Force’s 2022 advice reflects that trade-off¹:

• 60 and older: grade D, meaning don’t start daily aspirin for prevention.
• 40 to 59 with a 10-year heart risk of 10% or more: grade C, a personal decision, because the net benefit is small.
• Already taking it: it may be reasonable to consider stopping around 75, but don’t stop without talking to your clinician.

None of this applies to people who’ve had a heart attack or stroke, the Task Force says¹. The American College of Cardiology still advises low-dose aspirin for people with established artery disease, including past stents or bypass surgery⁵.

Cholesterol: before an event, risk sets the plan; after one, the goal is set

Cholesterol follows the same logic. On March 13, 2026, the American College of Cardiology, the American Heart Association and nine other groups published a new guideline on blood fats, replacing the 2018 version⁶.

Before a first event, the guideline sorts adults 30 to 79 by their estimated 10-year risk, using the Heart Association’s PREVENT calculator⁶. The risk groups are:

• Low: under 3%⁷.
• Borderline: 3% to under 5%, where LDL-lowering drugs “can be considered,” in the wording of the Heart Association’s summary⁶.
• Intermediate: 5% to under 10%, where they should be considered after a talk with your clinician, the same summary says⁶.
• High: 10% or more, with an LDL goal below 70, according to a summary by EBSCO’s DynaMed, a clinical reference service⁷.

DynaMed puts the LDL goal below 100 for people at borderline or intermediate risk, and it describes drug treatment in those groups a bit more firmly than the Heart Association does⁷. A coronary artery calcium scan, a CT picture of calcium in the heart’s arteries, can help sort people into the right group⁶.

After an event, the guideline stops asking whether to treat and starts asking how far. For people at very high risk, the LDL goal is below 55 mg/dL, and the guideline says most people who’ve had a heart attack or stroke will fall in that group⁶.

That firm goal rests on trials in people who already had heart disease. The best known is the Scandinavian Simvastatin Survival Study, or 4S, published in 1994. It enrolled 4,444 people in five Nordic countries who had angina or a past heart attack⁸.

Over a median of 5.4 years, 12% of the placebo group died, versus 8% on simvastatin⁸. The researchers estimated that for every 100 such patients treated for six years, the drug would save 4 of the 9 expected to die of heart disease⁸. Side effects led 6% to stop in both groups⁸.

One detail matters for natural-health readers. Everyone in 4S was already on a cholesterol-lowering diet before the trial began⁸. The statin’s benefit came on top of diet, not instead of it.

Guideline bodies don’t fully agree before a first event. The Task Force’s 2022 statin advice uses the older Pooled Cohort Equations and draws its lines at 10% (grade B) and 7.5% (grade C)⁹.

Our article on absolute risk covers statin numbers in people without heart disease. Our article on choosing health priorities shows how the 2025 blood pressure guideline applies similar risk logic.

Cancer: screening comes before, and preventing a return comes after

For cancer, secondary prevention in the public health sense means screening: finding cancer early in people who feel fine. A later article in this series covers how to weigh any screening test.

Breast cancer shows how the level changes a drug’s role. Tamoxifen, raloxifene and aromatase inhibitors can lower the odds of a first breast cancer. Over five years, per 1,000 women, they prevented about 7, 9 and 16 invasive cancers, the Task Force found in 2019¹⁰. The trials did not show fewer deaths from breast cancer or any cause¹⁰.

There were harms. Per 1,000 women over five years, tamoxifen added about 5 blood clots and 4 cancers of the uterine lining, and raloxifene about 7 blood clots¹⁰.

So the Task Force gave a split verdict. Grade B: offer these drugs to women 35 and older at increased risk and low risk of side effects. Grade D: don’t use them routinely in women who aren’t at increased risk¹⁰. Women with at least a 3% chance of breast cancer in the next five years are likely to gain more than they lose¹⁰.

After a diagnosis, the same drugs play a different role. The Task Force notes that aromatase inhibitors are mainly used to treat breast cancer, not to prevent a first one. Its advice doesn’t cover women who’ve had breast cancer or the early form called DCIS¹⁰. Those decisions belong with a cancer care team.

Quaternary prevention guards the healthy from too much medicine

The Belgian family doctor Marc Jamoulle devised quaternary prevention in 1986, according to a 2019 essay in the British Journal of General Practice and to Jamoulle’s own timeline¹¹¹³. He has described it as prevention aimed at medicine itself¹². In practice, it means spotting patients at risk of overmedicalization, shielding them from needless care and offering ethical alternatives¹¹. It entered the dictionary of the World Organization of Family Doctors, WONCA, in 2003¹³.

Its main target is overdiagnosis: finding a condition that would never have caused harm in a person’s lifetime¹¹. In that 2019 essay, Armando Henrique Norman and Charles Dalcanale Tesser named three common sources: screening, shifting the cutoffs that define a disease or risk factor, and financial incentives such as pay-for-performance schemes¹¹.

They also flagged a later-stage trap. In diabetes care, pushing blood sugar targets ever lower may bring more pills, a worse quality of life and higher death rates¹¹.

The aspirin reversal fits the idea well. For healthy older adults, taking a pill away was the protective step¹². A later article on hidden causes of balance problems covers medication reviews.

Lifestyle works at every level, but its job changes

Before a first event, habits do the heavy lifting. Our prevention-versus-treatment article covers the diabetes trial where a lifestyle program beat a drug.

After an event, lifestyle works alongside medicine, as the 4S diet detail shows⁸. Cardiac rehabilitation, a supervised program of exercise, education and coaching, is covered in our article on trainers and physical therapists. Our Mediterranean diet article covers trials in heart patients.

Here natural-health values and the evidence line up well. Doing the least that works is a sound instinct, and quaternary prevention is medicine’s own version of it.

But “least” depends on your level. For a healthy 70-year-old, skipping daily aspirin may be the safer choice¹. For someone recovering from a heart attack, declining aspirin or a statin gives up benefits shown in large trials⁴⁸.

Which level am I at? A decision table

This table is our own planning aid, built from the guidelines above. Use it to prepare for a visit.

Your situation	Level	What guidelines prioritize	Questions to ask
No known disease, normal numbers	Primary	Habits and age-based screenings; no new daily aspirin at 60 and older1	“What are my 10-year and 30-year risks?”
No heart disease, but borderline or higher 10-year risk	Primary, higher risk	A risk-based talk about a statin; a calcium scan may help decide67	“Which calculator did you use? Would a calcium score change the plan?”
A screening test found something early	Secondary (public health)	Confirm it, then decide whether and how to treat	“Could this have stayed harmless? What happens if we watch it?”
Past heart attack, stroke, stent or bypass	After an event	Low-dose aspirin for most; LDL below 55 for most56	“Was I referred to cardiac rehab? What’s my LDL goal?”
Treated for breast cancer	Tertiary	Treatment to prevent a return, planned with your cancer team10	“How much does this drug lower my risk of the cancer coming back?”
Many medicines, or tests piling up	Quaternary	Review what still helps; avoid overtreatment11	“Which of these is still doing me good?”

Call 911 right away for possible heart attack signs in you or someone near you. The CDC lists chest pain or pressure that may come and go; discomfort in the jaw, neck, back, arms or shoulders; shortness of breath; and feeling weak, faint or dizzy¹⁴. Sudden stroke signs also call for 911: numbness or weakness on one side, confusion or trouble speaking, trouble seeing or walking, or a sudden severe headache¹⁵.

What the evidence says

Claim	Evidence rating	What it rests on
Daily aspirin prevents repeat heart attacks and strokes in people with known vascular disease	Strong evidence	16 trials; about 15 fewer serious events per 1,000 people a year, by our math4
Starting daily aspirin helps healthy adults 60 and older	Evidence says no, or unsafe	ASPREE found more major bleeding and no fewer heart events; Task Force grade D12
Without heart disease, aspirin trims heart events slightly but adds bleeding	Strong evidence	6 pooled trials; Task Force grade C at 40 to 59, a small net benefit14
Statins save lives in people with heart disease	Strong evidence	Landmark trials such as 4S, where deaths fell from 12% to 8%68
Risk-reducing drugs prevent breast cancer in high-risk women	Strong evidence for fewer cases; deaths not shown to fall	7 to 16 fewer cancers per 1,000 over five years10
The same drugs help women not at increased risk	Evidence says no, or unsafe	Task Force grade D: harms outweigh benefits10

Questions readers ask

The bottom line

A preventive pill isn’t good or bad on its own. Its value depends on your starting risk, which depends on what has already happened to you. After a heart attack or stroke, aspirin and statins prevent many events per 1,000 people. Before one, the gains shrink and the harms stay put, so the choice turns personal.

Know your level, ask for numbers per 1,000 people like you, and treat both “take this to be safe” and “you don’t need that” as claims to check. If you already take something, make any change with your clinician.

Related reading

• Most heart attacks are preventable, and that doesn’t make treatment the enemy
• A 22% risk cut can mean helping 2 or 3 people in 1,000
• A trainer coaches your squat while a physical therapist treats what hurts
• Your family tree and free risk calculators can show you where to start
• A classic Mediterranean diet trial used canola oil, so the pattern travels well

Sources

1. U.S. Preventive Services Task Force. “Aspirin Use to Prevent Cardiovascular Disease: Preventive Medication.” Final recommendation statement, April 26, 2022. uspreventiveservicestaskforce.org
2. McNeil JJ, Wolfe R, Woods RL, et al. “Effect of Aspirin on Cardiovascular Events and Bleeding in the Healthy Elderly.” New England Journal of Medicine, 2018;379:1509-1518 (University of Iowa repository record). iro.uiowa.edu
3. American College of Cardiology. “Aspirin in Reducing Events in the Elderly (ASPREE).” Clinical trial summary, 2018. acc.org
4. Antithrombotic Trialists’ (ATT) Collaboration. “Aspirin in the primary and secondary prevention of vascular disease: collaborative meta-analysis of individual participant data from randomised trials.” The Lancet, 2009 (University College Cork research portal record). research.ucc.ie
5. American College of Cardiology. “New USPSTF Recommendation on Aspirin in CVD: No For Primary Prevention, Yes For Secondary Prevention.” ACC News, April 27, 2022. acc.org
6. American Heart Association. “Top Things to Know: 2026 Guideline on the Management of Dyslipidemia.” AHA Professional Heart Daily; guideline published March 13, 2026, in Circulation. professional.heart.org
7. EBSCO DynaMed. “EBM Focus: Top Takeaways From the Updated ACC/AHA Guideline on the Management of Dyslipidemia.” EBSCO Health Notes, 2026. about.ebsco.com
8. Scandinavian Simvastatin Survival Study Group. “Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study (4S).” The Lancet, 1994 (University of Oxford copy). ndph.ox.ac.uk
9. U.S. Preventive Services Task Force. “Statin Use for the Primary Prevention of Cardiovascular Disease in Adults: Preventive Medication.” Final recommendation statement, August 23, 2022. uspreventiveservicestaskforce.org
10. U.S. Preventive Services Task Force. “Breast Cancer: Medication Use to Reduce Risk.” Final recommendation statement, September 3, 2019 (update in progress as of October 2026). uspreventiveservicestaskforce.org
11. Norman AH, Tesser CD. “Quaternary prevention: a balanced approach to demedicalisation.” British Journal of General Practice, 2019;69(678):28-29. bjgp.org
12. Jamoulle M. “Quaternary Prevention, an Answer of Family Doctors to Overmedicalization.” International Journal of Health Policy and Management, 2015;4(2):61-64 (DOAJ record). pubmed.ncbi.nlm.nih.gov
13. Jamoulle M, Roland M, Tsoi G. “Quaternary prevention: an answer of family doctors to overmedicalization.” Poster, WONCA Asia Pacific Regional Conference, Taipei, March 2015 (record with timeline). docpatient.net
14. Centers for Disease Control and Prevention. “About Heart Attack Symptoms, Risk, and Recovery.” CDC, updated October 24, 2024. cdc.gov
15. Centers for Disease Control and Prevention. “Signs and Symptoms of Stroke.” CDC, updated May 19, 2026. cdc.gov