Low cholesterol linked to higher death rate: study

Having very low cholesterol was nearly as dangerous as having very high cholesterol, says Dr. Periaswamy Velevan, a research fellow in cardiology at the University of Hull in England.

"The low cholesterol levels were a predictor of higher mortality, which is contrary to what one would expect in patients with heart failure," he said. "You would expect the low cholesterol would be better. That was surprising."

But a Canadian cardiologist said it's difficult to reconcile the data with what several large clinical trials have found.

"We now have six very large trials of statin use [cholesterol-lowering drugs] in patients with heart disease, and these studies have more than 100,000 people in them, and in none of these studies where the cholesterol was lowered tremendously is there an increase in heart failure," said Dr. Jacques Genest, head of cardiology at Montreal's McGill University and a spokesman for the Heart and Stroke Foundation.

But, "I think this kind of study is really neat, because it's registry data and it may point to some interesting hypothesis worth examining in well-designed, controlled clinical trials."

An estimated 400,000 Canadians have heart failure, where the heart can no longer pump enough blood to the rest of the body. Blood can pool and back up into the liver, lungs and other organs.

Velevan said the role of cholesterol-lowering drugs in treating heart failure is controversial. Two large randomized trials are now underway.

The new study, presented Sunday at the American Heart Association's annual scientific meeting in Chicago, was based on the Euro Heart Failure survey, which involved 115 hospitals in 24 European countries.

Researchers looked at the relation between cholesterol, statins and the risk of dying within three months of being admitted. During that period, 1,425, or 12.5 per cent of the patients died.

The highest number of deaths was in people with cholesterol of less than 150 mg/decilitre of blood. People with a normal cholesterol (193 mg per decilitre of blood) and those taking statins had a better prognosis.

But the low cholesterol levels were associated with a higher risk of death. That appeared mainly true in the group with low cholesterol who were not taking statins. Older, frailer patients fared even worse.

It could be that statins help protect the heart in ways other than lowering cholesterol, by reducing inflammation, controlling heart rhythm and stabilizing plaques that can break off, lodge in a blood vessel and cause a heart attack.

"We know that in severe heart failure there is a major inflammatory response," Velevan said.
With heart failure, the general advice is to bring cholesterol down as much as possible with statins.

"But beyond a certain level, in advanced heart failure, it seems to be bad," he said.
Very low cholesterol may be a sign of more advanced heart failure, but Velevan cautioned more studies are needed to prove the link.