Larger and longer-term studies are needed to determine if the treatment will reduce the likelihood of having a heart attack, but the early results are promising, Dr. Daniel Rader, director of preventive cardiology at the University of Pennsylvania School of Medicine, wrote in an editorial that accompanied the study.
The 36 coronary heart disease patients in the study who received the treatment were given five weekly infusions of a laboratory-produced version of mutated high-density lipoprotein, or HDL. These patients received one of two concentrations of this good cholesterol that helps protect against heart disease by removing plaque, or fatty buildups, from the bloodstream.
Coronary heart disease occurs when plaque builds up inside the walls of blood vessels. The condition affects 12.6 million Americans, making it the most common form of heart disease. High blood cholesterol, high blood pressure and smoking are among the risk factors that can contribute to the buildup of plaque.
At six weeks, tests showed the patients receiving the synthetic protein had a visible 4.2 percent reduction in plaque buildup in their coronary arteries. The 11 patients in the control group who received a saline placebo had no decrease in the buildup on their arteries.
The quick results, though preliminary, contradict the long-standing belief that treating heart disease requires preventative therapies over long periods of time, Rader wrote in the editorial in the Journal of the American Medical Association.
The study’s findings stem from an unusual discovery about 25 years ago in a northern Italian village where researchers found that some residents had very low HDL levels, yet paradoxically had low rates of coronary artery disease. Further investigation revealed that the likely explanation was a gene variation in a key protein component of HDL. This mutation contributed to larger-than-normal HDL particles, which is believed to make them especially efficient at removing plaque.
Dr. Steven Nissen, a Cleveland Clinic cardiologist who led the study, wrote that he envisions the treatment might be used in combination with other therapies, including those that lower the levels of “bad” cholesterol.
Nissen also cautioned that “much more testing needs to be performed to determine whether this unique form of HDL can be used routinely to treat patients with atherosclerosis [plaque buildup on the arteries].” He also wrote in the journal article that his research was a small “proof of concept” study, designed only to demonstrate the potential of this new therapy.
While some existing medicines target HDL, most conventional drug treatments decrease levels of LDL cholesterol, the bad kind that can clog arteries and lead to heart attacks. Large clinical studies have shown that that lowering levels of LDL in the blood with the aid of cholesterol-lowering drugs, called statins, reduces the risk of coronary heart disease.
Nissen’s study is part of a new area of research focusing on treatments that raise HDL levels or improve its plaque-fighting abilities. If it is proven effective through large studies, it could show that raising HDL levels is as effective or possibly more effective in lowering the risk of heart disease as lowering the levels of LDL. Conducting these larger studies and then receiving approval from the Food and Drug Administration will likely mean that any new drugs would not be on the market before the end of the decade.
Wednesday’s study was funded by Esperion Therapeutics Inc. of Ann Arbor, Mich., a small biotechnology company that makes the patented synthetic version of HDL used by the researchers.