Omega n-3 Supplementation: Exploring the Cardiovascular Benefits Beyond Lipoprotein Reduction

Hypertriglyceridaemia is a highly prevalent disorder worldwide. Genetic and Mendelian randomization studies have suggested that triglyceride (TG)-rich lipoproteins are causal risk factors for coronary heart disease and contribute to the residual cardiovascular risk observed in patients optimally treated with statins. However, clinical trials failed to show cardiovascular benefits of TG-lowering; in this context, trials with omega-3 fatty acids provided contrasting results. Few trials have tested the supplementation of EPA alone rather than the combination of EPA + DHA. The JELIS study showed that EPA 1.8 g/day significantly reduced CV events in hypercholesterolaemic patients given statins, an effect that was independent on lipid reduction.

The REDUCE-IT trial showed that high-dose (4 g/day) EPA significantly reduces the incidence of major cardiovascular events compared with placebo in patients with elevated TG levels. The clinical benefit was higher than expected by the reduction of TG-rich lipoprotein levels. Recent data support the efficacy of high-dose EPA supplementation on a background of optimal LDL-C-lowering therapy as a key approach to achieve a further and significant reduction of CV events in very-high CV risk patients with persistent hypertriglyceridaemia. The effect on lipids does not appear to fully explain the CV benefit, and additional mechanisms of action of EPA likely contribute to the cardiovascular protection, including the reduction of inflammation and platelet aggregation. Current guidelines recommend using high-dose EPA in combination with a statin in high/very-high CV risk patients with mild-to-moderate elevation of plasma TG to reduce the residual CV risk.