CHICAGO – Detailed results of the REDUCE-IT trial have confirmed earlier-reported top line results that showed a 25% reduction in the risk of cardiovascular death or nonfatal cardiovascular event with the fish-derived, triglyceride-reducing agent icosapent acid in combination with statin.
But they should not be interpreted as validation of the cardiovascular benefits of fish-oil supplements, according to Deepak L. Bhatt, MD, principal investigator and steering committee chair for REDUCE-IT, who presented the results at the American Heart Association scientific sessions.
He reported the results from 8,179 patients followed for a median of 4.9 years. The treatment group received 4 g/day of icosapent ethyl (Vascepa, Amarin), a single-molecule agent consisting of the omega-3 acid known as eicosapentaeonoic acid (EPA) in ethyl-ester form, which Dr. Bhatt called “a highly purified” formulation. Vascepa is derived from fish but it is not fish oil, a company press release states. Amarin, sponsor of the study, released top line results in September.
To qualify for the trial, patients had to have a diagnosis of cardiovascular disease or diabetes and other risk factors, had been on statin therapy and had above normal triglyceride (135-499 mg/dL) and optimal LDL (41-100 mg/dL) levels. Patients were randomly assigned to receive 4 g/day of icosapent ethyl or placebo.
Dr. Bhatt stressed that the REDUCE-IT results do not necessarily validate the use of fish oil to lower cardiovascular risk. “It would be mistake if patients and physicians” to interpret the results that way, and that classifying the purified formulation of icosapent ethyl used in REDUCE-IT as fish oil is a “misnomer.” He added, “Really, what we’re talking about is prescription therapy icosapent ethyl vs. over-the-counter supplements.” Icosapent ethyl is approved in the United States for patients with triglyceride levels of more than 500 mg/dL.
Dr. Bhatt and the study coauthors acknowledged that the results of REDUCE-IT deviate from other trials of triglyceride-lowering agents, including other n-3 fatty acids. They noted two potential explanations: a high dose; or higher ratios of EPA to docosahexaenoic acid in the REDUCE-IT formulation vs. agents used in the other studies. For example, the ASCEND study, presented at the European Society of Cardiology in September, reported no cardiovascular benefit from a 1-g/day dose of omega-3 fatty acids and low-dose aspirin in patients with diabetes.
The primary endpoint of REDUCE-IT was a composite of cardiovascular death, nonfatal MI or stroke, coronary revascularization or unstable angina, which occurred in 17.2% of the patients taking icosapent ethyl, compared with 22% of the controls, for a risk reduction of 25% (P less than .001). The key secondary endpoint was composite of cardiovascular death and nonfatal MI or stroke, which occurred in 11.2% and 14.8% of the treated and placebo groups, respectively, for a risk reduction of 26% (P less than .001).
The study investigators also zeroed in on specific ischemic endpoints. Cardiovascular death rates were 20% lower in the treated patients (4.2% vs. 5.2%, P less than .03).
The study also evaluated lipid levels. The median change in triglyceride levels after a year of treatment was a decrease of 18.3%, or 39 mg/dL, in the treatment group while triglyceride levels rose 2.2% in the placebo patients (P less than .001). LDL levels increased in the treated patients by 3.1%, or 2 mg/dL (median) vs. 10.2%, or 7 mg/dL, in controls (P less than .001).
The trial also reported a 33% greater risk of hospitalization for atrial fibrillation or flutter and about a 30% heightened risk of serious bleeding among patients taking icosapent ethyl. Dr. Bhatt pointed out that, while the high rate of atrial fibrillation among treated patients was statistically significant, “the most feared complication of atrial fibrillation is stroke, but in this study we saw a 28% reduction in stroke.”
Likewise the nonsignificantly higher rate of bleeding in the treatment group was inconsequential. “When we looked at specific types of serious bleeding – GI or stomach bleeding, CNS or bleeding into the brain or fatal bleeding – there were no significant differences,” he said.
Discussant Carl Orringer, MD, of the University of Miami, said, “My perspective of this is that the likelihood of atrial fibrillation, although statistically higher, is something that should not prevent physicians from prescribing the drug because of the tremendous benefit that we’ve seen in those appropriate patients on high intensity statin.” However, he said, it does merit further investigation. He also pointed out that one limitation of the study was that the population was 90% white. “Thus the potential benefits of icosapent ethyl in patients of other ethnicities remains unclear,” he said.
The results were published simultaneously online in the New England Journal of Medicine.
Dr. Bhatt receives funding from Amarin, which sponsored the REDUCE-IT trial.
SOURCE: Bhatt DL, et al. N Engl J Med. 2018 Nov 10; doi: 10.1056/NEJMoa181279.