Recommendation 38: We suggest omega-3 polyunsaturated fatty acid (n-3 PUFA) therapy at a dose of 1 g daily be considered for reduction in morbidity and cardiovascular mortality in patients with HFrEF (Weak Recommendation, Moderate Quality Evidence).

Values and preferences: While there is an effect of fish oils on important HF outcomes, this recommendation also considers the modest effect size and issues surrounding the lack of standardization of commercial preparations in Canada.

• With most data, the dose of n-3 PUFA is 1 g/day. It is unknown whether higher or lower doses would confer clinical benefit and they are therefore not suggested. Doses greater than 3 g/day are associated with excessive bleeding.
• n-3 PUFA therapy may affect measures of anticoagulation. Close monitoring of the international normalized ratio in patients taking warfarin following institution of n-3 PUFA is suggested.
• There is evidence of significant variability in the content of n-3 PUFA. Patients considering n-3 PUFA should consult with their pharmacist to select a reliable supplement brand that most closely matches formulations shown to be effective in clinical trials.