Two studies being published today provide encouragement that some of the damaging effects of cholesterol on the heart may be reversible through diet and drugs.
Confirming the results of several previous studies of cholesterol in men, UC San Francisco researchers have shown that drug treatment and diet can begin to clear fatty deposits from clogged heart arteries in both sexes.
Their study, which examined 72 men and women who had clogged arteries but had yet to develop heart disease symptoms, is being published today in the Journal of the American Medical Assn. as part of a special issue on cholesterol and heart disease. Much of the research in the issue was sponsored by pharmaceutical manufacturers who make cholesterol-lowering drugs.
Another study in the journal, from the USC School of Medicine in Los Angeles, found that men who have had heart bypass surgery can continue to significantly lower the rate at which fatty deposits build up in their coronary arteries through a combination of cholesterol-lowering drugs and a low-fat diet. The results of the four-year study of 103 men extend the two-year USC results, which received wide publicity when they were published in 1987.
These trials, along with four others published earlier, “provide evidence that treatment will alter the natural history of atherosclerotic lesions--progression of lesions can be slowed, and existing lesions will regress,” according to an AMA journal editorial by Dr. Basil M. Rifkind of the National Heart, Lung and Blood Institute in Bethesda, Md., and Dr. Lawrence D. Grouse of Medical Communication Resources Inc. in Santa Monica.
All the studies used angiography--an X-ray inspection of the inside of the heart and blood vessels--to monitor changes in the degree of atherosclerosis. The technique is considered the most reliable way to demonstrate the clearing of clogged heart arteries. The trials included many different types of patients. They varied in cholesterol levels; some had no heart disease symptoms and others had severe symptoms.
It is widely accepted that high levels of cholesterol in the circulation can cause premature atherosclerosis, a form of hardening of the arteries in which the inner layers of artery walls become thickened and narrowed by deposits of fat, cholesterol and other substances. The two cholesterol-containing molecules most likely to cause these changes are known as low-density lipoproteins and very low-density lipoproteins.
In the heart arteries, a severe reduction in the flow of blood can have serious consequences, such as a heart attack, where heart muscle dies, or angina, a chest pain caused by an insufficient blood supply to heart muscle.
Most physicians regard a balanced diet that restricts saturated fats and cholesterol and the avoidance of obesity as the cornerstones of preventing atherosclerosis. In addition, physicians emphasize the importance of minimizing other heart disease risk factors, such as high blood pressure and smoking.
Prescription medications are usually only recommended for patients who cannot control cholesterol through diet, such as those genetically predisposed to elevated cholesterol levels. These medicines can cost from several hundred to several thousand dollars a year.
The UC San Francisco study, led by Dr. John P. Kane, included 41 women and 31 men with elevated cholesterol levels. All were advised to change their diets. About half received cholesterol-lowering drugs, such as niacin, colestipol and lovastatin.
After two years, the blockage of heart artery lesions increased an average of 0.8% in the patients treated with diet. It decreased an average of 1.53% in the patients treated with diet as well as drugs.
For women, the blockage of the heart artery lesions increased an average of 1.07% for those treated with diet. It decreased an average of 2.06% in the women treated with diet as well as drugs.
A 1988 study by another team of UC San Francisco researchers showed that a strict vegetarian diet combined with moderate exercise and relaxation techniques such as yoga could begin to clear heart artery lesions without the use of drugs.
Patients in the USC study, led by Dr. Linda Cashin-Hemphill and Dr. David H. Blankenhorn, were randomly assigned to treatment with diet and colestipol and niacin or treatment with the diet and a placebo pill. After four years, many of the patients in both groups had progressive coronary artery disease, but the patients treated with diet and drugs generally fared better.
For example, about 15% of the drug-treated patients developed new heart artery blockages, compared to about 39% of placebo-treated patients, according to the report. And 18% of the drug-treated patients had blockages that started to reverse, compared to 6% of placebo-treated patients.
Two other articles discussed the use of cholesterol measurements in children.
Researchers at the University of Iowa in Iowa City reported on the long-term results of a study of cholesterol levels in 2,367 children who were tracked into adulthood. The study found that many children with elevated cholesterol levels had normal levels when they were tested again as young adults, without any specific diet changes or drug treatment.
“Many children with high cholesterol levels do not become adults with high cholesterol levels,” wrote Drs. Ronald M. Lauer and William R. Clarke.
A separate team of researchers at UC San Francisco argued that “children should not be screened for high blood cholesterol levels” because the benefits of such screening “are unlikely” to exceed the risks.
Among the risks cited by the UC San Francisco researchers, Drs. Thomas B. Newman, Warren S. Browner and Stephen B. Hulley, were the expense of screening, the potential for family conflicts triggered by abnormal test results, and evidence that lowering cholesterol levels later in life “will be nearly as effective” in reducing the risks of heart disease. In addition, they cited prior studies in adults that have inexplicably linked cholesterol reduction with a statistically increased risk of death from accidents, suicide and violence.
The researchers wrote: “The first two decades of life are a time when many other things are more important than cholesterol--like growth, surviving adolescence, and enjoying ice cream.”