Lipid Tests and Cardiovascular Risk

Most individuals get periodic testing of traditional lipid panels including total cholesterol, LDL, HDL, and triglycerides. While these have some utility, they either only tell part of the story or are not interpreted in the most optimal way. To better understand cardiovascular risk, apolipoprotein B (apoB) levels should accompany all lipid tests levels and all patients should be screened for elevations of lipoprotein a (LPa). This data can also be combined with measures of inflammation, a known cause of blood vessel damage. Taken together, with a detailed personal and family history, a clearer picture of individuals’ risk of heart disease, stroke, and other vascular diseases can be created.

LDL

LDL has traditionally been called the “bad” cholesterol, while HDL is considered to be “good” or protective. This is an oversimplification of the true mechanisms by which lipids cause damage to blood vessels. It turns out that the compound that actually causes the thickening and hardening of the blood vessel walls through buildup of plaques (atherosclerosis) is called apolipoprotein B (apoB). In human bodies, the majority of apoB is bound to LDL - in this way, measuring LDL levels is an indirect way of measuring the apoB concentration I the blood. HDL, by comparison, carries apolipoprotein A (apoA), which helps remove cholesterol from the blood vessels and reduce inflammation and damage.

ApoB

Because apoB is directly implicated in the development of atherosclerosis in the blood vessels of the heart, brain, and other organs, it is a superior biomarker to LDL cholesterol. Reducing apoB, either through diet or cholesterol-lowering medications, is known to reduce the risk of death from cardiovascular causes.

Lp(a)

Lp(a) is a unique form of LDL which is known to be especially damaging to arteries and valves of the heart. It has a linear association with heart attack, stroke, and aortic valve stenosis (the higher the level of Lp(a), the higher the risk of those diseases). Approximately 20% of people have elevated Lp(a) levels, which is known to be genetically inherited. Lp(a) levels don’t fluctuate much and while there are clinical trials underway for medications to reduce it, currently there is no approved treatment to lower it for prevention. Patients should have this test done once during their life, and, if elevated, take steps to optimize all other parameters of cardiovascular risk.

Inflammatory Markers

It has long been understood that the damage caused by lipids in the arteries is related to the inflammation that they cause - immune cells trying to repair the damage, cause inflammation and scaring, resulting in plaques that can narrow and occlude critical arteries (atherosclerotic cardiovascular disease). Combining tests for inflammation such as high-sensitivity C-reactive protein (hs-CRP) and homocysteine alongside lipid tests provide a more clear picture of short and long-term risk of cardiovascular disease.