The Role of Cholesterol in Cardiovascular Disease – Part 1

The puzzle of cardiovascular disease.

Cardiovascular disease kills over 800,000 people in the US every year, most of whom would be alive today if they had received currently available and affordable treatment. Unlike other diseases, cardiovascular disease progresses in small steps every year, starting in early adulthood and manifesting with symptoms such as a heart attack or stroke after decades of its slow and methodical advancement. Unfortunately, science lacks the tools required to diagnose these initial microscopic stages leading to treatment that is either delayed or never started, leaving people to suffer the debilitating consequences of this disease. 

The misunderstanding of cholesterol and its role in the development of this disease, paired with a constant stream of misinformation from various sources, has further complicated a relatively simple formula for dramatically decreasing the incidence of cardiovascular disease. A mountain of research has shown that cholesterol and the development of atherogenic plaques (the growths that form inside of arteries and disrupt their function) are inextricably linked. 

Much of the controversy stems from the nuance in this relationship. Physicians use cholesterol level, specifically, LDL-cholesterol level (the amount of cholesterol found within the low density lipoprotein particles), to screen people for increased cardiovascular risk. This level, paired with a host of other factors such as blood sugar, triglyceride level, blood pressure, diet, and lifestyle, just to name a few, are like puzzle pieces. The more pieces the physician uses and the greater their understanding of how those pieces fit into the puzzle, the better and more exact the final picture of risk. 

The level of cholesterol in the blood plays an important role in this puzzle. However, the amount of detail it gives to the final picture varies and must be taken within the context of the entire puzzle. In some instances it can, by itself, produce a clear image. However, in others, it can fool the medical provider by creating a distorted view of risk. 

The lipid profile of the patient with type 2 diabetes provides an excellent example of a situation where looking only at cholesterol level provides a deceptive picture of risk. The LDL cholesterol level of these patients is typically within the “normal” range. Most medical providers, however, understand that these patients are at extraordinarily high risk for cardiovascular disease despite their LDL cholesterol level. Such apparent discrepancies between LDL cholesterol and risk have led some to argue that cholesterol level is not a useful indicator of risk. 

To some extent, this is true. The role of cholesterol in the formation of atherogenic plaques is more complex than can be entirely encompassed by the measurement of blood cholesterol. The cholesterol level is used as a surrogate marker, or shortcut, for a much more complex relationship. A review of what a cholesterol test measures will help to place its value as a risk predictor in context. 

We will discuss this in part 2 of this series.