Good cholesterol scientifically termed as HDL and bad cholesterol known as LDL are known to play a significant role in determining the total cholesterol count in the human body. In order to remain healthy individuals are usually advised to increase the HDL level and decrease the LDL level. But a ground-breaking study has astonishingly revealed that a high level of HDL probably elevated the risk of coronary events such as chest pain, heart attack and death in a subgroup of patients.
The study authors employed a high-profile Pfizer clinical trial testing torcetrapib which is an experimental drug to possibly know the effects of increase in the levels of HDL cholesterol. Then with a graphical data mapping tool they noted down all the outcomes of the study. The authors observed a higher risk of coronary events among a group of patients with greater level of HDL but the reasons were unclear.
“It seems counterintuitive that increasing good cholesterol, which we’ve always thought of as protective, leads to negative consequences in some people. We’ve confirmed that high HDL cholesterol is in fact associated with risk in a certain group of patients,” remarkedJames Corsetti, M.D., Ph.D., professor of Pathology and Laboratory Medicine at the University of Rochester Medical Center and lead author of the study.
The high risk sub-group patients displayed high levels of C-reactive protein (CRP) which is known as an inflammation marker. Elevation in the HDL cholesterol supposedly takes place due to genetics and environmental factors, particularly inflammation. They are usually protective but if their level increases they seem to enhance cardiovascular risks. A novel set of genes in an individual can probably determine if the present level of HDL cholesterol will be beneficial or not, but this can happen only in an inflammatory environment.
Charles Sparks, M.D., professor of Pathology and Laboratory Medicine and co-author of the study said, “The ability to identify patients who will not benefit from efforts to increase HDL cholesterol is important because they can be excluded from trials testing medications that aim to raise HDL cholesterol. With these patients excluded, researchers may find that raising HDL cholesterol in the remaining population is effective in reducing cardiovascular disease risk.”
Two genetic factors which are also apparently associated with repetitive coronary events were discovered in the patients belonging to the high-risk subgroup with extreme levels of HDL. The risk to coronary events may be heightened due to the activity of cholesterol ester transfer protein (CETP) and p22phox. CETP is usually associated with HDL cholesterol and is assumed to shift the cholesterol away from the vascular system.
Corsetti informed, “Our research is oriented around the ability to better identify patients at high risk. Identifying these patients and determining what puts them at high risk may be useful in choosing treatments tailored to the specific needs of particular patient subgroups. This gets us another step closer to achieving the goal of personalized medicine.”
Among 767 non-diabetic patients, the authors were successful in finding individuals with an elevated risk for recurring coronary events. They all had previously undergone at least one heart attack and around 20 percent of the patients belonging to the subgroup, displayed an elevated level of HDL cholesterol and CRP.
The study was published in Arteriosclerosis, Thrombosis, and Vascular Biology, a journal of the American Heart Association.