We’ve all heard about the importance of raising HDL, or the so-called “good” cholesterol, and lowering LDL, or “bad” cholesterol, to improve heart health.
While we’ve come to assume HDL cholesterol is an inherently good thing, a new study shows that for a certain group of patients, this is not always the case. The study is the first to find that a high level of the supposedly good cholesterol places a subgroup of patients at high risk for recurrent coronary events, such as chest pain, heart attack, and death.
The findings, published in Arteriosclerosis, Thrombosis, and Vascular Biology, a journal of the American Heart Association, could help explain disappointing results from a high-profile Pfizer clinical trial testing torcetrapib, an experimental drug designed to increase levels of HDL cholesterol, that some predicted would become a blockbuster medicine. The trial was halted in 2006 due to a surprisingly excessive number of cardiovascular events and death. As in the current study, cardiovascular events in the torcetrapib trial were associated with higher levels of “good” HDL cholesterol, though 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,” said James Corsetti, M.D., Ph.D., professor of Pathology and Laboratory Medicine at the University of Rochester Medical Center and lead author of the study. “We’ve confirmed that high HDL cholesterol is in fact associated with risk in a certain group of patients.”
Using a novel graphical data mapping tool – outcome event mapping – Corsetti and his team identified a group of patients in which elevated levels of HDL cholesterol place them in a high-risk category for coronary events.
“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,” said Charles Sparks, M.D., professor of Pathology and Laboratory Medicine and co-author of the study. “With these patients excluded, researchers may find that raising HDL cholesterol in the remaining population is effective in reducing cardiovascular disease risk.”
Despite the outcome of the Pfizer torcetrapib trial and findings in the existing literature, including the current study, that suggest high HDL cholesterol can be a bad thing, drug companies remain invested in identifying drugs to increase HDL cholesterol. Merck recently announced plans to launch a major clinical trial in 2011 to test whether anacetrapib – a molecular cousin to torcetrapib designed to raise good cholesterol – reduces the risk of heart attack and death.
Patients in the high-risk subgroup were characterized as having high levels of C-reactive protein (CRP), a well-known marker of inflammation, in addition to high HDL cholesterol. Study authors believe genetics and environmental factors, particularly inflammation, influence whether high levels of HDL cholesterol are protective or if they increase cardiovascular risk in individual patients. Given an inflammatory environment, an individual’s unique set of genes helps determine whether HDL cholesterol transforms from a good actor to a bad actor in the heart disease process.
In the high-risk subgroup of patients with elevated HDL cholesterol and CRP, researchers also identified two genetic factors associated with recurrent coronary events. The activity of cholesterol ester transfer protein (CETP), which moves cholesterol away from the vascular system and is associated with HDL cholesterol, and p22phox, which influences inflammation-related processes and is associated with CRP, are both risk predictors in this subgroup of patients.
“Our research is oriented around the ability to better identify patients at high risk,” said Corsetti. “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.”
Corsetti’s team identified individuals at high risk for recurrent coronary events among 767 non-diabetic patients who experienced at least one prior heart attack. About 20 percent of the total study population was in the subgroup having high-risk with high HDL cholesterol and CRP. Outcome event maps plot risk over an area defined by high and low levels of two biomarkers, in this case HDL cholesterol and CRP. Peaks and valleys in the maps correspond to high- and low-risk patient subgroups. Patients were followed for recurrent events for approximately two years and were part of the Thrombogenic Factors and Recurrent Coronary Events (THROMBO) study led by cardiologist Arthur Moss, M.D., professor of Medicine at the University of Rochester Medical Center and study co-author.
The current results parallel findings from a study of a healthy population. The Prevention of Renal and Vascular End-Stage Disease (PREVEND) study also identified a high-risk subgroup of patients with elevated HDL cholesterol and CRP levels among individuals who had no prior coronary events.
In addition to Corsetti, Sparks, and Moss, Dan Ryan, M.D., and Wojciech Zareba, M.D., Ph.D. from the University of Rochester Medical Center and David Rainwater, Department of Genetics, Southwest Foundation for Biomedical Research, San Antonio, Texas participated in the study. The study was funded by the National Heart, Lung and Blood Institute at the National Institutes of Health.For Media Inquiries:
Emily Butler | EurekAlert!
3D images of cancer cells in the body: Medical physicists from Halle present new method
16.05.2018 | Martin-Luther-Universität Halle-Wittenberg
Better equipped in the fight against lung cancer
16.05.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
23.05.2018 | Life Sciences
23.05.2018 | Life Sciences
23.05.2018 | Physics and Astronomy