Top U.S. heart doctors warned Sunday at the American College of Cardiology’s annual meeting in Chicago that millions of people taking Merck & Co. and Schering-Plough Corp.’s pills Vytorin and Zetia should instead be getting older drugs proven to reduce the risk of death.

“The strongest recommendation we can make on this panel is to go back to Statins. They work,” said Dr. Harlan M. Krumholz, a cardiologist at Yale, according to the New York Times.

The panel’s recommendation followed the presentation of a controversial study known as Enhance that found the drugs failed to show they worked any better than a cheaper generic statin in patients with an inherited form of heart disease.

The same recommendation also came in an editorial in the New England Journal of Medicine published Sunday.

Vytorin is a combination of Merck’s statin Zocor and Zetia, which was developed by Schering-Plough. The companies market them through a joint venture. Vytorin and Zetia had more than a combined $5 million in annual sales last year, although prescription levels have dropped since the beginning of the year after the initial results from the study were released in January. About five million people worldwide, including four million Americans, take the medicines, which have been heavily advertised to consumers in the U.S.

“We know statins are good rugs and we know they reduce risks. We believe in general to get to a $5 billion-a-year drug, there was a lot of premature use of ezetimibe before the statin option had been exhausted,” Krumholz told a media briefing after the panel.

The two drugs received the Food and Drug Administration approval on the basis that they reduced levels of LDL, or bad cholesterol and doctors have long believed that lowering LDL slows the advance of heart disease. In the Enhance trial, the drugs did lower cholesterol levels more than a statin but neither reduced the thickening of a neck artery in trial subjects.

Following the panel’s recommendation, the manufacturers released a joint statement Sunday saying the drugs were effective and that they planned to continue marketing them as primary treatments for heart disease.

“We were very disappointed in the ACC panel. We had expected a balanced discussion and we really didn’t think the panel today served patients well. We were particularly concerned because we know of no safety concerns that should be raised after the Enhance trial. But we know a lot about the value of LDL-lowering and that is what we had hoped the scientific discussion would address,” Dr. Robert Spiegel, chief medical officer of Schering-Plough told Reuters.

A large trial looking at Vytorin’s impact on death and heart attack rates had been scheduled to finish in 2011, but researchers announced Friday that they are expanding the number of patients to as many as 18,000 from 12,500 because there have been fewer adverse events than expected. The estimate now is that the study will be finished in 2012.