REDUCE-IT

Cardiovascular Risk Reduction with Icosapent Ethyl for Hypertriglyceridemia

D. L. Bhatt, et al. for the REDUCE-IT Investigators

N Engl J Med. 2019 Jan 3;380(1):11-22. doi: 10.1056/NEJMoa1812792. [Full Text]


Summary by Abra Guo

Elevated triglyceride (TG) levels are known to be a marker for ischemic events, and while medications such as niacin and fibrates reduce TG levels they have not been shown to decrease ischemic events. Similarly Omega acids have been disappointing [1,2].

Icosapent ethyl is a purified form of eicosapentaenoic acid, a type of omega-3 fatty acid. Prior studies that laid the groundwork for REDUCE-IT include MARINE and ANCHOR studies, which showed that twelve-week treatment with icosapent ethyl reduced triglyceride levels by 33.1 and 21.5% respectively [3]. The Japan EPA Lipid Intervention Study (JELIS), was a prospective, unblinded / open-label study of 18,645 patients that found that the risk of composite events, which included sudden cardiac death, fatal and non-fatal myocardial infarction, unstable angina, and revascularization were 19% lower in patients who received Icosapent ethyl and statin therapy vs statin therapy alone [4].

REDUCE-IT was a international multicenter, randomized, double-blind, placebo-controlled trial aimed to examine if icosapent ethyl would reduce cardiovascular events in comparison to placebo. One major consideration is that mineral oil was used as the placebo to mimic the omega taste; however, mineral oil is thought to confer increased CV risk.

Patient population

8179 patients who had cardiovascular disease or diabetes and at least one additional risk factor who were currently on statin therapy were enrolled. Patients also had residual hypertriglyceridemia, with a fasting triglyceride level between 150-499 mg/dl. Exclusion criteria included those with severe heart failure, active severe liver disease, an A1c > 10.0%, and those with planned coronary intervention or surgery. The median age was 64 years, with 28.8% of patients being female, and 90% of patients being white.

Patients were randomized to either receive icosapent ethyl 2 g twice daily or mineral oil placebo. Randomization was stratified to a primary-prevention cohort (capped at 30% of patients) or secondary-prevention cohort. 

Outcomes

The primary outcome was a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, coronary revascularization, or unstable angina. Median follow-up period was 4.9 years.

The key secondary end point was a composite of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke. Additional endpoints included cardiovascular death, myocardial infarction, and hospitalization for unstable angina. 

Results

Most patients were white (~90%) and male (~71%), and most were recruited in the secondary prevention arm (~70%).

17.2% of patients in the icosapent ethyl group experienced primary end-point events, compared with 22.0% of patients in the placebo group (HR, 0.75; 95% confidence interval, 0.68 to 0.83; P<0.001). The NNT to prevent a primary outcome in one patient was 21.

11.2% of patients in the icosapent ethyl group experienced key secondary endpoint events, compared with 14.8% of the patients in the placebo group (HR, 0.74; 95% CI, 0.65 to 0.83; P<0.001). The NNT to prevent one key secondary end-point event was 28.

The icosapent ethyl group had a higher risk of atrial fibrillation (5.3% vs. 3.9%, p<0.001) and equal frequency of pneumonia (2.6% vs. 2.9%, p=0.42).

Discussion

Among white patients with known cardiovascular disease or risk factors for cardiovascular disease on statin therapy, concomitant use of icosapent ethyl was shown to lower the risk of major cardiovascular events compared to a mineral oil placebo.

Though this trial did demonstrate a significant decrease in the risk of other secondary endpoints including cardiovascular death (4.3% vs. 5.2%; HR, 0.80; 95% CI, 0.66 to 0.98; P=0.03), myocardial infarction (6.1% vs. 8.7%; HR, 0.69; 95% CI, 0.58 to 0.81; P<.001), and hospitalization for unstable angina death (2.6% vs. 3.8%; HR, 0.68; 95% CI, 0.66 to 0.98; P=0.03), it should be noted the absolute risk reduction between these is modest.

The findings are promising but it should be noted that the beneficial effects seem to be out of proportion to the amount TGs were lowered or the anti-inflammatory effects seen in CRP reduction [1]. In light of numerous prior negative fish oil studies [2], the unknown impact of mineral oil use as a placebo, and that icosapent ethyl may currently be cost-prohibitive (wholesale price of $334.30 for a month supply [5]) it is unlikely that these results change current management of hypertriglyceridemia without future confirmation.


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