OMEGA-3 fatty acids compared to placebo in secondary prevention of myocardial reinfarction

Abstract

While much research has been done investigating omega-3 polyunsaturated fatty acids and the primary prevention of coronary heart disease, few studies focus on secondary prevention of myocardial reinfarction in populations with established coronary heart disease. Further, studies that examine omega-3 polyunsaturated fatty acid therapy in patients with established coronary heart disease have shown an inconsistent association between omega-3 polyunsaturated fatty acid intake and the risk of myocardial reinfarction. This study aims to investigate the cardioprotective properties of long chain omega-3 fatty acids.

Methodology: A systematic review of evidence-based literature was performed using Medline and Cochrane databases. Studies reviewed include randomized controlled trials, meta-analyses and systematic reviews of randomized controlled trials, and cohort studies. Studies reviewed included the following criteria: 1) randomized trials comparing dietary or supplemental intake of omega-3 fatty acids with a control diet or placebo, 2) trials reporting cardiac endpoints such as fatal or nonfatal myocardial infarction and overall mortality, 3) trials following patients with established coronary heart disease for at least 6 months.

Results: Ten studies make up the literature review of this evidence based medicine report. Five of these studies are Level 1 randomized controlled trials, two are Level 1 metaanalyses of randomized controlled trials, and three are Level 2 prospective cohorts. Evidence-based studies show that incorporating fatty fish or omega-3 fatty acids supplementation into the diet reduces all cause mortality between 15-30%. Results also show a decrease in myocardial reinfarction of 20-25% with supplementation of omega-3 iv fatty acids. Perhaps the strongest evidence to incorporate omega-3 fatty acids into the diet is the prevention of cardiac arrhythmias and sudden cardiac death. Studies report an 11-81% decrease in sudden cardiac death due to fatal cardiac arrhythmias. Although individual studies reviewed showed a decrease in morbidity and mortality due to coronary heart disease, when compared their findings were inconsistent.

Conclusion: The majority of the literature shows a decrease in myocardial reinfarction in patients already diagnosed with coronary heart disease with the incorporation of fatty fish intake or supplementation with long chain omega-3 fatty acids. However, the quality of studies conducted to this point is suboptimal and more studies are needed to confirm and further define the health benefits of omega-3 fatty acids for preventing subsequent cardiovascular events. At this time there is insufficient evidence to make a recommendation to include omega-3 fatty acids for prevention of myocardial reinfarction in patients with existing coronary heart disease.