According to recent European Medicines Agency report omega-3 fatty acid medicines are not effective in preventing further heart problems after a heart attack. Omega-3 fatty acid medicines should no longer be used in this way. However, they can still
be used to reduce levels of certain types of blood fat called
triglycerides. Omega-3 fatty acid medicines have been authorised for use after a heart
attack, in combination with other medicines, in several EU countries
since 2000, at a dose of 1 g per day.Previously it was believed that some benefits in reducing serious problems with the heart and blood vessels.
It concluded that, although there are no new safety concerns, the
effectiveness of these medicines in preventing recurrence of problems
with the heart and blood vessels has not been confirmed.
Ref:
https://www.ema.europa.eu/en/medicines/human/referrals/omega-3-acid-ethyl-esters-containing-medicinal-products-oral-use-secondary-prevention-after
https://www.bfarm.de/SharedDocs/Risikoinformationen/Pharmakovigilanz/EN/RV_STP/m-r/omega-3-fettsaeuren.html