MUNICH -- Omega-3 fatty acid supplementation failed to prevent cardiovascular events in yet another study, this time a placebo-controlled trial reported here.
With mean follow-up of 7.4 years, patients with diabetes (n=15,480) who were randomized to daily 1-g capsules of omega-3 fatty acids had the same odds of non-fatal MI or stroke, transient ischemic attack, or cardiovascular death as peers who got olive-oil placebo (8.9% versus 9.2%, RR 0.97, 95% CI 0.87-1.08), reported Louise Bowman, MD, of the University of Oxford in England, at the annual congress of the European Society of Cardiology (ESC).
The ASCEND study results were also simultaneously published online in the .
Consideration of arterial revascularization in addition to serious vascular events still yielded no difference between groups (11.4% versus 11.5%, RR 1.00, 95% CI 0.91-1.09). No difference was seen for all-cause death either (9.7% versus 10.2%, RR 0.95, 95% CI 0.86-1.05). Additionally, the omega-3 and placebo groups shared similar rates of non-fatal serious adverse events (most commonly surgical/medical procedures).
The results add to the growing literature that omega-3 consumption makes no difference in cardiovascular health, despite published guidance still recommending it to reduce the risk of congestive heart failure, coronary heart disease, ischemic stroke, and sudden cardiac death, the investigators noted.
"Our results would suggest that current guideline recommendations should be reconsidered," Bowman said in a press conference.
Louise Bowman, MD, presenting the results
Clinicians could also use ASCEND to nudge patients toward therapies that actually work in primary prevention, suggested Christopher Cannon, MD, of Brigham and Women's Hospital in Boston. As it currently stands patients may think they're doing something beneficial with their fish oil pills, so they don't take a statin, he commented as trial discussant during the ESC session.
However, another take on the study could also be that omega-3 supplementation didn't work specifically on a background of statin therapy, as three-quarters of patients were taking statins, according to William Zoghbi, MD, of Houston Methodist DeBakey Heart & Vascular Center.
"The study also does not negate the possible beneficial effect of fish intake in the diet because of other possible health confounders in fish," said Zoghbi, who is a past president of the American College of Cardiology and wasn't involved in the trial.
Participants in ASCEND had no evidence of atherosclerotic cardiovascular disease upon enrollment. Adherence to the assigned treatment was 76% overall.
Another caveat to the study was that triglycerides were not tracked, although previous research suggested they can be reduced by omega-3 fatty acids. Additionally, it remains possible that a higher dose might have shown an effect in the primary endpoint, Bowman acknowledged.
For now, one trial to watch out for is the ongoing VITAL trial testing vitamin D and higher-dose omega-3 supplementation in the primary prevention of cancer and cardiovascular disease, the authors noted.
Other upcoming trials of note are REDUCE-IT and STRENGTH, according to Peter Toth, MD, PhD, of CGH Medical Center in Sterling, Illinois, who said he holds onto hope that omega-3 fish oils are beneficial agents.
"The REDUCE-IT and STRENGTH trials will be much better studies to more fully elucidate and test the value of omega-3 fish oils in the setting of elevated risk and hypertriglyceridemia because they are using a full therapeutic dose of 4 grams," he told ѻý.
Disclosures
The study was funded by institutional grants from the British Heart Foundation and non-financial support from Cancer Research U.K., Bayer, Solvay, Abbott, and Mylan.
Bowman also disclosed a grant from the Medical Research Council.
Zoghbi reported no conflicts of interest.
Cannon declared a relationship with Amarin, the maker of an omega-3 drug.
Primary Source
New England Journal of Medicine
Bowman L, et al "Effects of n-3 fatty acid supplements in diabetes mellitus" N Engl J Med 2018; DOI: 10.1056/NEJMoa1804989.