Omega-3 fatty acid supplements may offer cardiovascular protection

Supplementation with omega-3 fatty acid may have a dose-related protective effect on coronary events. Furthermore, there may also be a dose-related adverse effect on non-fatal arrhythmias, according to recent additional data from the ASCEND trial.

Although higher fish consumption has long been associated with lower risks of coronary heart disease (and especially of cardiac deaths in observational studies), the evidence so far has been inconclusive with conflicting outcomes in various studies and meta-analyses [1-3]. Prof. Sarah Parish (University of Oxford, United Kingdom) presented additional data of the randomised ASCEND trial which assessed the effects of omega-3 fatty acid supplementation on arrhythmias from linkage to electronic Hospital Episode Statistics data during trial for 97% of patients (and for 14 years before randomisation). A total of 15,480 UK patients were included, aged ≥40 years, who had diabetes (any type) and no prior cardiovascular disease. Current use of anticoagulation was an exclusion criterium. Patients were equally randomised to omega-3 fatty acids 1 g capsule/day vs placebo and aspirin 100 mg daily vs placebo. Mean follow-up was 7.4 years; >99% complete follow-up for morbidity and mortality. The average adherence to omega-3 capsules was 77%.

Researchers specifically aimed at arrhythmia outcomes defined as hospitalisations or serious events reported by participants during the trial, and ICD10-code diagnoses and OPCS4 procedure codes in electronic Hospital Episode Statistics data. Key outcomes were atrial fibrillation (AF) in participants without known prior AF, non-fatal ventricular arrhythmia, and any non-fatal cardiac arrhythmia and cardiac death. With regard to non-fatal arrhythmias, the rate ration (95% CI) was 1.02 for AF, 1.49 for ventricular arrhythmia, and 1.05 for any cardiac arrhythmia. For cardiac deaths, the rate ratio was 0.79 for coronary death, 0.78 for non-coronary cardiac death and 0.79 for any cardiac death.

“Thus, ASCEND provides randomised evidence of the effects of 1 g daily omega-3 fatty acid capsules on arrhythmias, without statistically significantly effect on AF or on any non-fatal cardiac arrhythmia,” Prof. Parish said. She also mentioned that these findings require systematic reporting of arrhythmia outcomes in existing and future trials. “The ongoing STRENGTH trial using 4 g daily supplementation will be able to add important information when it completes in 2020 [4].”

1. Aung T, et al. [JAMA Cardiol. 2018;3(3):225-233](https://jamanetwork.com/journals/jamacardiology/fullarticle/2670752).
2. Manson, [N Engl J Med. 2019; 380:33-44](https://www.nejm.org/doi/full/10.1056/NEJMoa1809944).
3. Bhatt DL, et al. [N Engl J Med. 2019; 380:11-22](https://www.nejm.org/doi/full/10.1056/NEJMoa1812792).
4. Parish S, et al. Effects of omega-3 fatty acid supplements on arrhythmias in the ASCEND study. FP Number 186. ESC Congress 2019, 31 Aug-4 Sept, Paris, France.

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Posted on 10 October, 2019