Higher Serum Omega-3 Tied to Better Outcome After STEMI

Debra L. Beck

October 27, 2020

Regular consumption of foods rich in omega-3 fatty acids was associated with improved prognosis after ST-segment myocardial infarction (STEMI) in a new observational study.

The prospective study, which involved 944 patients with STEMI who underwent primary percutaneous coronary intervention (PCI), showed that plasma levels of fatty acids at the time of the STEMI were inversely associated with both incident major adverse cardiovascular events (MACE) and cardiovascular readmissions (adjusted hazard ratio, 0.76 and 0.74 for 1-SD increase; for both, P < .05).

No association was seen for the endpoint of all-cause mortality.

"What we showed is that your consumption of fish and other sources of omega-3 fatty acids before the heart attack impacts your prognosis after the heart attack. It's a novel approach because it's not primary prevention or secondary prevention," said Aleix Sala-Vila, PharmD, PhD, from the Institut Hospital del Mar d'Investigacions Mèdiques (IMIM) in Barcelona, Spain.

Sala-Vila, co–senior author Antoni Bayés-Genís, MD, PhD, Heart Universitari Germans Trias I Pujol, Barcelona, and first author Iolanda Lázaro, PhD, also from IMIM, reported their findings online October 26 in the Journal of the American College of Cardiology.

It has been established that dietary omega-3 eicosapentaenoic acid (EPA) has cardioprotective properties, but observational studies and randomized trials of EPA intake have yielded disparate findings.

This study avoided the usual traps of nutritional epidemiology research — self-reported food diaries and intake questionnaires. For this study, the researchers measured tissue levels of EPA and alpha-linolenic acid (ALA) by measuring serum phosphatidylcholine (PC) levels, which reflect dietary intake during the previous 3 or 4 weeks.

This technique, said Sala-Vila, not only provides a more reliable measure of fatty acid intake over time but also avoids measurement errors related to fatty acid content variation.

For example, "The EPA content of a piece of fish eaten in January could be very different from one eaten in June," explained Sala-Vila.

That said, he acknowledged that this technique, which uses gas chromatography, does not at present have a clear clinical application. "It's quite difficult just to convert levels of serum-PC EPA into consumption of fatty fish. We feel that the best advice at this point is that given by the American Heart Association to eat two servings of fatty fish a week."

EPA and ALA: Partners in Prevention?

In addition to the findings regarding EPA, the researchers also found that serum-PC ALA was inversely related to all-cause mortality after STEMI (HR, 0.65 for 1-SD increase; P < .05).

A trend was seen for an association between ALA and lower risk for incident MACE (P = .093).

ALA is readily available from inexpensive plant sources (eg, chia seeds, flax seeds, walnuts, soy beans) and has been associated with lower all-cause mortality in high-risk individuals.

This omega-3 fatty acid is often given short shrift in the fatty acid world because of the seven-step enzymatic process needed to convert it into more beneficial forms.

"We know that the conversion of ALA to EPA or DHA [docohexaenoic acid] is marginal, but we decided to include it in the study because we feel that this fatty acid is becoming more important because there are some issues with fish consumption — people are concerned about pollutants and sustainability, and some just don't like it," explained Sala-Vila.

"We were shocked to see that the marine-derived and vegetable-derived fatty acids don't appear to compete, but rather they act synergistically," said Sala-Villa. The researchers suggested that marine and vegetable omega-3 fatty acids may act as "partners in prevention."

"We are not metabolically adapted to converting ALA to EPA, but despite this, there is a large body of evidence showing that one way to increase the status of EPA and DHA in our membranes is by eating these sources of fatty acids," said Sala-Vila.

For almost 20 years, Sala-Vila has been studying how the consumption of foods rich in omega-3 affects disease. Two of his current projects involve studying levels of ALA in red blood cell membranes as a risk factor for ischemic stroke and omega-3 status in individuals with cognitive impairment who are at high risk for Alzheimer's disease.

Applicable to All Patients With Atherosclerosis

In comments to theheart.org | Medscape Cardiology, Deepak Bhatt, MD, called the study "terrific," adding that the effort is "as good as it gets" for observational nutrition research.

"I think one has to view these findings in the larger universe of what is really a revolution in omega-3 fatty acid research," said Bhatt.

This universe, he said, includes a wealth of observational research showing the benefits of omega-3s, two outcome trials — JELIS and REDUCE-IT — that showed the benefits of EPA supplementation, and two imaging studies — EVAPORATE and CHERRY — that showed favorable effects of EPA on the vasculature.

REDUCE-IT, for which Bhatt served as principal investigator, showed that treatment with icosapent ethyl (Vascepa), a high-dose purified form of EPA, led to a 25% relative risk reduction in MACE in an at-risk Western population.

The results, said Bhatt, who co-wrote an editorial that accompanies the current Sala-Vila article, "likely apply to all patients with atherosclerosis or who are at high risk for it" and supports the practice of counseling patients to increase their intake of food rich in omega-3 fatty acids.

The field may be due for a shake-up, he noted. At next month's American Heart Association meeting, the results of another trial of another prescription-grade EPA/DHA supplement will be presented, and they are expected to be negative.

AstraZeneca announced in January 2020 the early closure of the STRENGTH trial of Epanova after an interim analysis showed a low likelihood of their product demonstrating benefit in the enrolled population.

Epanova is a fish-oil derived mixture of free fatty acids, primarily EPA and DHA. It is approved in the United States and is indicated as an adjunct to diet to reduce triglyceride levels in adults with severe (≥500 mg/dL) hypertriglyceridemia. This indication is not affected by the data from the STRENGTH trial, according to a company press release.

Sala-Vila has received grants and support from the California Walnut Commission, including a grant to support part of this study. Bayés-Genís and Bhatt have relationships with a number of companies.

J Am Coll Cardiol. 2020;76:2089-97. Published online October 26. Full text, Editorial

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