n-3 polyunsaturated fatty acids (fish oil) after myocardial infarction

Last reviewed 05/2023

There is contrasting evidence for the benefits of omega -3 fatty acids (n-3 polyunsaturated fatty acids) in patients with ischaemic heart disease

Asystematic review of the literature on the effects of omega-3 fatty acids (n-3 FAs) (consumed as fish or fish oils rich in eicosapentaenoic acid and docosahexaenoic acid or as alpha-linolenic acid) on cardiovascular disease outcomes and adverse events was conducted (1)

• the authors concluded that the evidence suggests that increased consumption of n-3 FAs from fish or fish-oil supplements, but not of alpha-linolenic acid, reduces the rates of all-cause mortality, cardiac and sudden death, and possibly stroke. The evidence for the benefits of fish oil is stronger in secondary- than in primary-prevention settings

n-3 PUFAs and arrhythmias

• some authors state that the early effect of low-dose (1 g/d) omega-3 fatty acids on total mortality and sudden death supports the hypothesis of an antiarrhythmic effect of this drug. Such a result is consistent with the wealth of evidence coming from laboratory experiments on isolated myocytes, animal models, and epidemiological and clinical studies (2)
• a systematic review and meta-analysis investigating the role of fish oil on arrhythmias and mortality however concluded that (3):
  • fish oil supplementation was associated with a significant reduction in deaths from cardiac causes but had no effect on arrhythmias or all cause mortality

n-3 PUFAs in chronic heart failure

• there is evidence from the GISS-HF Investigators that n-3 PUFAs reduce morbidity and mortality in chronic heart failure (4)

• note however that:

  • among patients with a recent episode of sustained ventricular arrhythmia and an implantable cardioverter defibrillator (ICD), fish oil supplementation did not reduce the risk of ventricular tachycardia (VT)/ ventricular fibrillation (VF) and may be proarrhythmic in some patients (5)

NICE state (6):

• do not offer or advise people to use the following to prevent another MI:
  • omega-3 fatty acid capsules
  • omega-3 fatty acid supplemented foods

Reference:

• 1) Wang C et al. n-3 Fatty acids from fish or fish-oil supplements, but not alpha-linolenic acid, benefit cardiovascular disease outcomes in primary- and secondary-prevention studies: a systematic review. Am J Clin Nutr. 2006 Jul;84(1):5-17
• 2) Circulation. 2002 Apr 23; 105(16): 1897-903.
• 3) Leon H et al. Effect of fish oil on arrhythmias and mortality: systematic review.BMJ. 2008; 337: a2931.
• 4) Gissi-HF Investigators. Effect of n-3 polyunsaturated fatty acids in patients with chronic heart failure (the GISSI-HF trial): a randomised, double-blind, placebo-controlled trial.Lancet. 2008 Oct 4;372(9645):1223-30
• 5) Raitt MH et al. Fish oil supplementation and risk of ventricular tachycardia and ventricular fibrillation in patients with implantable defibrillators: a randomized controlled trial. JAMA 2005;293:2865-72
• 6)NICE (2013).MI - secondary prevention Secondary prevention in primary and secondary care for patients following a myocardial infarction