An elevated blood level of a molecule produced by liver damage also appears to predict the risk of heart disease and stroke, according to an Austrian study published in the Sept. 27 issue of Circulation.

The researchers report that men with even moderately high levels of the molecule, called gamma-glutamyl transferase, were at a 28-percent-higher risk of dying from cardiovascular disease than were those with low levels. For men with the highest levels, the risk was 68 percent greater. In women the increase in risk ranged from 35 percent to 51 percent, the researchers found.

The study was done as a follow-up to an Italian report linking elevated GGT levels to atherosclerosis, the "hardening of the arteries" that leads to heart disease and stroke, according to a statement by study author Hanno Ulmer, an associate professor of medical statistics at Innsbruck Medical University.

Ulmer and his colleagues used medical data on nearly 164,000 Austrian participants in a long-running health-monitoring program.

A follow-up of more than 11 years found that an elevated GGT level was a better predictor of cardiovascular death than high levels of blood sugar and cholesterol, but not as good a predictor as two other major risk factors, smoking and high blood pressure.

A blood test for GGT is widely used to monitor liver function.

For example, many doctors give it routinely to people who take cholesterol-lowering statins, where liver damage is a possible side effect.

But, Ulmer says, "beyond its role as an indicator of liver function, GGT is very likely to predict cardiovascular disease."

There are two possible reasons why GGT is a marker for cardiovascular disease, Ulmer says. One is that it is an indicator of general damage to the arteries. Alternatively it could indicate the damage done to blood vessels by heavy drinking. The Austrian researchers could not rule out the possibility that heavy drinking was the only cause of elevated levels, because they did not have information on alcohol consumption by the study participants.

Further studies are needed to determine the value of GGT testing to assess cardiovascular risk, Ulmer says, adding that it should be included as a major parameter in future cardiovascular-intervention studies.

More studies are necessary, agrees Dr. JoAnn Manson, a professor of medicine at Harvard Medical School in Cambridge, Mass., and a spokeswoman for the American Heart Association.

"It isn't clear whether it is an independent indicator if you rule out other biomarkers of cardiovascular risk," she says.

The nature of the Austrian study "makes it difficult to tease out the confounding effect of alcohol consumption," Manson adds.

"It is an interesting study that warrants confirmation in other populations, especially where you can control for alcohol intake in detail and other biomarkers of risk."

National Library of Medicine