One of the key factors of the leading cause of death in the United States, coronary artery diseases, is the hardening of arterial walls through buildup of fat, cholesterol and excessive waste produced by cells, a process known as atherosclerosis.
Atherosclerotic buildup, or plaque, can significantly block or alter blood flow in the arteries that supply the oxygen-dependent heart muscle.
Plaques can also rupture, causing blood loss and muscle damage. These blockages and ruptures can trigger long-term weakening of the heart and, often, heart attacks.
Understanding the causes and risk factors that contribute to the development and onset of atherosclerosis and plaque rupture will provide insight for developing better treatments and preventative measures for coronary syndromes.
Ruptures are responsible for up to 75 percent of all acute heart problems.
Bruce Wasserman's team of researchers at the Department of Radiology and Radiological Sciences at the Hopkins School of Medicine, in association with doctors in the Department of Pathology, studied cardiovascular risk factors that are associated with atherosclerosis.
Wasserman's group analyzed data from the Multi-Ethnic Study of Atherosclerosis (MESA), a long-term study following healthy individuals, some of whom could go on to develop heart disease.
As the name suggests, the study included members of several ethnic minorities from across the country. The goal of this study organization was to appreciate any differences in risk factors that might be associated with ethnic or racial background.
Initially, a total of 6,814 participants free of cardiovascular disease history were selected to participate in the study at six locations across the country.
Wasserman and his group used ultrasound and MRI to identify individuals with thickening of the arterial walls, which is characteristic of atherosclerosis. MRI studies were also used to find plaques and lipid cores.
Lipid cores are large accumulations of fat that can be deposited in an artery, usually near a wall, and can serve as the "seed" for further plaque growth. Even a small amount of lipid in an artery can attract large amounts of cholesterol and other fats, eventually leading to severe fat buildup and atherosclerosis.
To measure known cardiovascular risk factors, blood was drawn immediately after the MRI test and again within a 30-day window.
Both high-density lipoprotein, commonly termed "good" cholesterol for its ability to reduce cholesterol buildup in arteries, and low-density lipoprotein cholesterol or "bad" cholesterol were measured and analyzed along with blood pressure and body mass index.
The study showed that the presence of a lipid core was significantly related to carotid wall thickness but not so much with other factors such as smoking and hypertension.
The association between cholesterol and lipid cores was still strong even in patients who used lipid-lowering medication.
Of the major risk factors associated with atherosclerosis, plasma cholesterol levels are strongly associated with the presence of lipid cores.
This association is still significant even after adjustments for carotid artery thickness, medication use, and the presence of other risk factors such as smoking and diabetes.
This study is particularly significant because it involved a large pool of ethnically diverse participants, so the results are more related to the pathological causes of plaque rupture and atherosclerosis than external environmental and lifestyle factors that are already well-studied.
This also largely corrected the biased results from previous studies of the same problem.
Ultimately, the results of this study can be applied to develop better methods of recognizing plaque formation before it endangers the heart muscle.
