Written by Joyce Smith, BS. The OMEMI trial found that treatment with 1.8 g n-3 PUFAs daily for 2 years did not reduce the incidence of cardiovascular events or all cause death in elderly patients with a recent acute myocardial infarct (MI).
Studies have shown an association between supplementation with polyunsaturated fatty acids (PUFAs) and a reduced risk of cardiovascular (CV) events. Elderly populations following MI have a high risk of subsequent CV events in spite of lipid-lowering and antiplatelet therapies 1. Yet, this very vulnerable group is grossly underrepresented in CV clinical trials, and recommended treatments and doses are based on the study results of younger populations 2,3. Past studies have been inconsistent in demonstrating that 3-nPUFA intake can reduce the risk of CV events in subjects with CVD.
Thus the OMEMI (Omega-3 fatty acids in Elderly patients with Myocardial Infarction) trial 4 was designed to assess whether omega-3 fatty acid supplements can reduce the risk of CV events in elderly patients with a recent acute MI. This multicentered, double-blinded, placebo-controlled trial enrolled 1,027 patients, 70-82 years of age, who were hospitalized with a recent acute MI. They were randomized 2-8 weeks after hospitalization to receive 1.8 g daily of omega-3 fatty acids (93 mg of eicosppentaenoic acid [EP] and 660 mg of docosahexaenoic acid [DHA]) versus a corn oil placebo in addition to standard care.
Most participants (97%) were taking statins to lower cholesterol levels and 86% were on two blood thinners. The primary outcome included non-fatal MI, unscheduled revascularization (stenting or bypass surgery), stroke, HF hospitalization, or all-cause mortality. The secondary outcome was new-onset of atrial fibrillation (AF). Major bleeding outcomes were used to measure safety.
A two-year follow up revealed a similar rate of cardiac events (≈20 %) between the two groups. Omega 3 fatty acid supplementation in MI patients had no effect on the primary CV outcome of non-fatal MI, unscheduled revascularization (stenting or bypass surgery), stroke, HF hospitalization, or all-cause mortality (P=0.62) compared to placebo (P=0.97).
There was also a non-significant increased risk of AF in patients taking omega-3 fatty acid supplements compared to placebo (P=0.06) and no difference in major bleeding outcomes between the two groups. The secondary outcome of new-onset AF was non-significantly higher (7.2%) in the PUFA group compared to 4% in the placebo group. Serum EPA and DHA measurement taken at baseline and repeated at study’s end demonstrated good adherence to treatment protocol.
This study adds to the accumulating evidence against the use of EPA/DHA omega-3 fatty acid formulations and suggests an inability to provide cardiovascular benefits for older, high risk post-MI patients. In this 2-year follow up study, more patients were registered with first time episodes of atrial fibrillation in the n-3 PUFA group compared to the placebo group. The higher incidence of atrial fibrillation among PUFA recipients is consistent with data from other omega-3 fatty acid studies and given the absence of omega-3 fatty acid benefit and its demonstrated potential risk of harm, the researchers believe that all EPA/DHA formulations should not be recommended to patients.
Why, in the OMEMI trial, were the omega-3 fatty acid supplements no more effective than the placebo in improving cardiovascular outcome and decreasing all-cause death in elderly patients who had recent MIs? One hypothesis is that DHA may be less biological active or may even counteract the potential benefits of EPA. Additional trials to compare results are warranted.
Source: Kalstad, Are Annesønn, Peder Langeland Myhre, Kristian Laake, Sjur Hansen Tveit, Erik Berg Schmidt, Pal Smith, Dennis Winston Trygve Nilsen et al. “Effects of n-3 Fatty Acid Supplements in Elderly Patients after Myocardial Infarction: A Randomized Controlled Trial.” Circulation (2020).
Posted January 12, 2021.
Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.
References:
- Jernberg T, Hasvold P, Henriksson M, Hjelm H, Thuresson M, Janzon M. Cardiovascular risk in post-myocardial infarction patients: nationwide real world data demonstrate the importance of a long-term perspective. Eur Heart J. 2015;36(19):1163-1170.
- Gurwitz JH, Col NF, Avorn J. The exclusion of the elderly and women from clinical trials in acute myocardial infarction. Jama. 1992;268(11):1417-1422.
- Heiat A, Gross CP, Krumholz HM. Representation of the elderly, women, and minorities in heart failure clinical trials. Arch Intern Med. 2002;162(15):1682-1688.
- Kalstad AA, Myhre PL, Laake K, et al. Effects of n-3 Fatty Acid Supplements in Elderly Patients after Myocardial Infarction: A Randomized Controlled Trial. Circulation. 2020.
