Eicosapentaenoic acid (EPA), an omega-3 polyunsaturated fatty acid primarily found in fish oil, has been scientifically investigated for its potential benefits in cardiovascular diseases, including congestive heart failure (CHF). The evidence supporting its use in CHF is moderate, with several clinical studies and meta-analyses suggesting that omega-3 supplementation may offer some benefit, though the effect size is modest.

The most notable scientific support comes from the GISSI-HF trial (2008), a large, randomized, placebo-controlled study involving over 6,900 patients with chronic heart failure. The study found that supplementation with 1 gram daily of omega-3 fatty acids (EPA and DHA combined) resulted in a small but statistically significant reduction in all-cause mortality and cardiovascular hospitalizations compared to placebo. Other meta-analyses have corroborated these findings, showing that omega-3 supplementation can modestly improve left ventricular function and may reduce inflammation, arrhythmias, and progression of heart failure.

Mechanistically, EPA is thought to exert its effects by reducing systemic inflammation, improving endothelial function, and stabilizing cardiac cell membranes. However, it should be noted that most studies used combined EPA/DHA supplements, and the individual effect of EPA alone is less well established. Guidelines from major cardiology organizations recognize omega-3s as adjunct therapy in heart failure, particularly for patients who remain symptomatic despite standard treatments.

In summary, the use of EPA (typically in combination with DHA) for CHF is supported by moderate scientific evidence, with potential, albeit modest, benefits for mortality and cardiac function.