Omega-3 After a Heart Attack, in Heart Failure and for Secondary Prevention
What GISSI trials, newer trials, meta-analyses and heart-society statements found for omega-3 after a heart attack and in heart failure, and why care stays with cardiology.
Content last updated . This page has not been medically reviewed.
Older trials gave the strongest signals for omega-3 after a heart attack and in heart failure; newer trials and pooled analyses are less clear. In GISSI-Prevenzione (1999), 1 g per day of n-3 fatty acids was linked to fewer deaths. [1] In GISSI-HF (2008), a similar amount was linked to a small advantage in heart failure. [2] Later analyses found no significant link between omega-3 supplements and coronary events in people with prior coronary disease. [3] People with heart disease should discuss omega-3 with their cardiology team, not decide alone. This page is information, not advice.
Chest pain, fainting or sudden breathlessness: call 911 (US).
How to read the labels
"Mixed" means results differ across trials. "Insufficient evidence" means too little to say. Each result belongs to the product, amount, group and comparison named. Study amounts are not advice.
Evidence table
| Question | What the source found | Strength |
|---|---|---|
| After a recent heart attack: GISSI-Prevenzione | 11,324 patients surviving a recent heart attack were assigned n-3 PUFA (1 g daily), vitamin E, both, or none for 3.5 years. [1] n-3 PUFA but not vitamin E lowered the primary endpoint (death, nonfatal heart attack, stroke). [1] | Older randomized trial; control group received no supplement |
| Heart failure: GISSI-HF | 6,975 patients with chronic heart failure (class II to IV) were assigned n-3 PUFA 1 g daily or placebo for a median 3.9 years. [2] Deaths from any cause were 27% versus 29% (adjusted HR 0.91). [2] | One large randomized trial; small absolute difference |
| Older adults after a heart attack: OMEMI | 1.8 g per day of EPA plus DHA versus corn oil, ages 70 to 82, 2 years. [4] The authors could not detect a reduction in clinical events. [4] | One trial; mixed against the older trials |
| Pooled trials in high-risk people | Ten trials, 77,917 people, EPA doses 226 to 1,800 mg per day: no significant association with fatal or nonfatal coronary disease or major vascular events. [3] | Meta-analysis |
| Another pooled analysis | A 2019 meta-analysis of 13 trials reported lower rates of heart attack and coronary death, even excluding REDUCE-IT. [5] | Meta-analysis; conclusions differ from the one above |
| Cochrane review | Moderate- and high-quality evidence suggests that increasing EPA and DHA has little or no effect on mortality or cardiovascular health. [6] | Systematic review |
The two pooled analyses reached different conclusions on related questions; one pooled 10 trials and the other 13, and they used different outcome definitions. [3] [5]
What heart societies said
- American Heart Association advisory (2017, before several newer trials): for people with prior coronary heart disease it rated omega-3 supplement treatment "reasonable" (Class IIa, Level A); for secondary prevention in heart failure, "reasonable" (Class IIa, Level B-R, based on one large trial, GISSI-HF). [7] It made no recommendation for primary prevention in the general population. [7] The advisory notes that the panel did not reach consensus on that indication, with some preferring a weaker Class IIb. [7]
- ESC/EAS dyslipidaemia guideline (2019), as returned by our web-reading tool: in the section on acute coronary syndromes it says routine treatment with n-3 PUFAs cannot be recommended, and it notes that antithrombotic effects may raise bleeding, especially with aspirin or clopidogrel. [8] We could not read the guideline's recommendation tables, so we do not report their classes.
Because the 2017 advisory predates several trials in the table, it may not reflect all current practice. Check with a cardiology team.
Limits
- GISSI-Prevenzione enrolled patients between October 1993 and September 1995, so its results may not carry to people on current treatment. [1]
- Purified EPA (REDUCE-IT) and a carboxylic-acid form (STRENGTH) were studied in people with high triglycerides, a different group from heart-attack survivors. [9] [10] See prescription omega-3 vs supplements.
- The AHA advisory notes that 91% of the patients in GISSI-HF had heart failure with reduced ejection fraction, which limits how far the findings apply to other kinds of heart failure. [7]
Frequently asked questions
Does fish oil help after a heart attack?
Results differ. GISSI-Prevenzione linked 1 g per day to fewer events, while OMEMI found no reduction in older adults and pooled analyses disagree. [1] [4] [3]
Is omega-3 a heart failure treatment?
The AHA advisory rated it "reasonable" based on one large trial, GISSI-HF. [7] It is not a substitute for heart failure medicines.
Should I take fish oil with my heart medicines?
Ask your cardiology team or pharmacist. Interactions, including bleeding, are possible. [8]
Is prescription omega-3 the same as a supplement?
No. Products differ in form and amount. See prescription omega-3 vs supplements.
Can omega-3 prevent a second heart attack by itself?
The sources do not show that. Cochrane found little or no effect overall. [6]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety and who should ask first
- Omega-3 products can interact with blood thinners and antiplatelet medicines: medication interactions. Do not stop a prescribed heart medicine without your prescriber.
- Atrial fibrillation was more often reported in some high-amount trials: fish oil and atrial fibrillation. In OMEMI, major bleeding was similar between groups (10.7% and 11.0%). [4]
- In GISSI-HF, stomach and bowel symptoms were the most frequent side effect (3% in each group). [2]
- Tell your surgical team: supplements before surgery. For kidney or liver disease, ask a clinician. See omega-3 evidence by use.
References
- Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Lancet 1999. Read 2026-10-22.
- Effect of n-3 polyunsaturated fatty acids in patients with chronic heart failure (the GISSI-HF trial). Lancet 2008. Read 2026-10-22.
- Associations of omega-3 fatty acid supplement use with cardiovascular disease risks: meta-analysis of 10 trials involving 77 917 individuals. JAMA Cardiol 2018. Read 2026-10-22.
- Effects of n-3 fatty acid supplements in elderly patients after myocardial infarction: a randomized, controlled trial (OMEMI). Circulation 2021. Read 2026-10-22.
- Marine omega-3 supplementation and cardiovascular disease: an updated meta-analysis of 13 randomized controlled trials involving 127 477 participants. J Am Heart Assoc 2019. Read 2026-10-22.
- Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev 2018. Read 2026-10-22.
- Siscovick DS et al., Omega-3 polyunsaturated fatty acid (fish oil) supplementation and the prevention of clinical cardiovascular disease: a science advisory from the American Heart Association. Circulation 2017 (full text read on PubMed Central). Read 2026-10-22.
- 2019 ESC/EAS Guidelines for the management of dyslipidaemias, Eur Heart J 2020;41:111. Text read through a web-reading tool; recommendation tables were not readable. Read 2026-10-22.
- Cardiovascular risk reduction with icosapent ethyl for hypertriglyceridemia (REDUCE-IT). N Engl J Med 2019. Read 2026-10-22.
- Effect of high-dose omega-3 fatty acids vs corn oil on major adverse cardiovascular events in patients at high cardiovascular risk (STRENGTH). JAMA 2020. Read 2026-10-22.