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.
“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, 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.
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.
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. 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, 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.
References:
1. James Corsetti, et al. Cholesteryl Ester Transfer Protein Polymorphism (TaqIB) Associates With Risk in Postinfarction Patients With High C-Reactive Protein and High-Density Lipoprotein Cholesterol Levels. Arterioscler Thromb Vasc Biol, May 2010; doi:10.1161/ATVBAHA.110.207977
