Confidence Drops in Prescription-Strength Fish Oil

More than 13,000 patients, treated at centers around the world, were given either Epanova or a placebo pill containing corn oil. All patients had conditions putting them at at “high cardiovascular risk.” For example, they were being treated with cholesterol-lowering statins and had either blockages of the coronary arteries, or arteries in the brain or legs, or were at risk for heart disease because of conditions such as diabetes or lifestyle risk factors like smoking.

Enrollment into the trial began in 2014. The trial was terminated in January of 2020, Lincoff’s group said.

Over that period of time, over 1,600 patients experienced some kind of cardiac event . But the use of Epanova did not decrease deaths from heart disease, heart attack, stroke, the need for stents or bypass surgery, or being hospitalized for angina.

There was even one downside to the treatment: Researchers say that use of the prescription-strength fish oil appeared tied to a rise in the risk for the common abnormal heart rhythm called atrial fibrillation.

But if Epanova appears to confer no benefit, why did heart patients given another omega-3 prescription drug, Vascepa, seemingly get a health boost?

According to Curfman, the answer may lie in trial design.

Vascepa contains a form of purified EPA known as icosapent ethyl. The clinical trial which appeared to validate Vascepa’s effectiveness lasted 5 years. Researchers found that use of the drug was tied to a 25% reduction in a variety of cardiac events when compared to placebo — in this case, mineral oil.

“Why did these 2 high-quality clinical trials, both using the same high dose of omega-3 fatty acids, come to opposite conclusions?,” Curfman asked.

The choice of placebo — mineral oil or corn oil — might help explain the discrepancy, he said. Perhaps Vascepa “did not reduce the risk of cardiovascular events, but instead, the comparator, mineral oil, increased the risk of cardiovascular events,” Curfman theorized. That might create the illusion that Vascepa helped patients, he reasoned.

There is some evidence that mineral oil can boost levels of LDL ‘bad” cholesterol, Curfman noted.