November 20, 1998

Researchers track benefits of lowering cholesterol further

Researchers track benefits of lowering cholesterol further

reporter_11.20.98_5.jpg (36k)

Dr. MacRae Linton is studying whether lowering LDL cholesterol levels even further will cut the risk of heart attack. (Photo by Donna Jones Bailey)

How low should you go?

Several landmark studies have demonstrated that lowering the levels of so-called bad cholesterol in people with heart disease can significantly reduce their heart attack risk.

Now researchers are tackling the next question: would a more aggressive reduction in LDL-cholesterol to lower levels be even better? Vanderbilt University Medical Center is participating in a large, multi-national study designed to determine just that.

"It's an important question," said Dr. MacRae F. Linton, associate professor of Medicine and Pharmacology and director of VUMC's Lipid Clinic.

"The previous studies have all shown a 30 percent to 40 percent reduction in cardiac events. The question is, why can't we do better than that? There may be other factors involved, but one possibility is that we're not lowering LDL-cholesterol enough."

An estimated 33 million people in the United States and Europe have coronary artery disease.

Large epidemiological studies have established that low levels of LDL cholesterol are associated with a reduced risk of incidence and death from "cardiovascular events" such as myocardial infarction (heart attack). As a result, an LDL cholesterol level of 100 mg/dL or lower is recommended for patients with established coronary artery disease.

The new study, called Treating to New Targets or TNT, is the first to examine whether the clinical benefit to patients treated to an LDL level of about 75 mg/dL is greater than that seen in patients treated to the current standard.

Evidence from another study, the Post-Coronary Artery Bypass Graft trial, suggested that more aggressive lowering of LDL cholesterol results in less progression of coronary artery disease. The goal of the TNT study is to determine whether that will translates into better clinical outcomes.

Patients with documented coronary artery disease will be treated with a cholesterol-lowering medication called atorvastatin, which was launched commercially last year. Patients will be randomly assigned to two groups: one with an LDL-lowering goal of 100 mg/dL and the other with a goal of 75 mg/dL.

The industry-sponsored study will compare incidence of coronary death or non-fatal myocardial infarction in the two groups.

The five-year trial will involve more than 8,500 patients at 250 sites in the United States, Canada, Europe, South Africa and Australia.

"The patients who would qualify for the study should be treated anyway," Linton said. "All patients will at least be treated to the standard cholesterol-lowering guidelines, while the rest will be treated to even lower levels."

Atorvastatin is generally well-tolerated with only mild and transient adverse reactions. The manufacturer reports gastrointestinal discomfort as the most frequent side effect.

To qualify for the study, individuals must have pre-existing coronary artery disease (prior heart attack or chest pain and an abnormal EKG, stress test or angiogram). They also must have an LDL cholesterol level of between 130-250 mg/dL when off cholesterol-lowering medications. (Individuals already taking cholesterol-lowering medications may be eligible).

For more information about participating in the study, please call clinical nurse practitioner Beth Meador, the study cooridinator, at 936-1653.