High Cholesterol May Increase Risk Of Plaque Rupture

When blood vessels are narrowed, stiffened or clogged by cardiovascular disease, organs and tissues cannot get the blood, oxygen, and nutrients that they need to function. This could cause serious complications and possibly death. A recent study has shown that high cholesterol not only contributes to the formation of plaques on blood vessel walls, it can also make these plaques more likely to break apart and cause life-threatening blood clots.

What Makes Up the Plaque?

A plaque is made up of two major parts - a lipid (or fatty) core and an overlying fibrous cap. Having more of a fibrous cap and less of a lipid core can keep the plaque stable and prevents it from breaking off. However, if the plaque is made up of more of a lipid core and less of a fibrous cap, it is more likely to rupture. This triggers the body's clotting mechanism, and the clot can further impede blood flow, leading to a heart attack or stroke.

High Cholesterol May Increase Risk Of Plaque Rupture

Researchers at Johns Hopkins University in Baltimore, Maryland measured carotid intima media thickness in more than 200 people who did not have symptoms of heart disease. This was performed by measuring the thickness of plaque in the carotid arteries, the major vessels that supply the brain with blood, with magnetic resonance imaging (MRI). Along with measuring the thickness of plaque in the carotid arteries, they also looked at the risk factors for heart disease that these individuals had, which included diabetes, high blood pressure, high cholesterol, smoking, and inflammation.

They found that high cholesterol was associated with lipid cores, while all the other risk factors did not have this association. In fact, 71% of individuals with high cholesterol levels had more of a lipid core in their plaque. (In this study, they considered total cholesterol levels greater than 226 mg/dL to be "high".) While this is slightly higher than the current guidelines, which recommend that total cholesterol levels should be below 200 mg/dL, their results still suggest that the higher cholesterol levels are, the more likely a lipid core will be present in the plaque. This higher lipid content in the plaque could cause the plaque to become unstable, which could increase the likelihood of the plaque breaking apart and causing a large clot.

While we are already aware of the role that high cholesterol levels play in plaque formation in vessels of the body, this study suggests that high cholesterol levels might also play a role in whether or not the plaques rupture.

_Sources:

Wasserman BA, Sharren AR, Lai S et al. Risk factor associations with the presence of a lipid core in carotid plaque of asymptomatic individuals using high resolution MRI: the MESA study. Stroke. 39:329-335).