ApoB & Your Heart Health
A Primer on the Latest in Cardiovascular Disease Prevention
It’s up to doctors to always have a hand on the pulse of the latest medical information, assessing whether the studies coming out represent a meaningful change in how we should best care for patients.
No place is this clearer in my mind than when measuring cholesterol.
Why High Cholesterol Matters
Measuring cholesterol is important because high cholesterol is:
a silent killer,
a common disease, and
a condition we can actually do something about.
High cholesterol is one of the first major steps on the path to heart disease, otherwise known as atherosclerosis.
In essence, cholesterol shuttled through the bloodstream in LDL (low density lipoprotein) particles gets deposited into blood vessel walls, triggering an inflammatory cascade that ultimately causes the formation of plaque. Over time, these plaques clog the arteries, and may even dislodge and completely occlude a smaller, downstream vessel, resulting in a devastating heart attack or stroke.
Perhaps the worst part of all is that, until that event occurs, you may not have any symptoms at all.
Even worse, unfortunately, is that this process is not rare. In fact, heart disease is the number one killer in America of adults over 40, with nearly 25% of deaths being attributed to cardiovascular disease.
If that’s the case, shouldn’t we be doing everything possible to detect and prevent it?
Since the vast majority of heart disease is preventable, it makes sense to direct our attention to finding the right combination of diet, exercise, and medications (when needed) to treat high cholesterol, decrease the risk of developing fulminant heart disease, and prevent a catastrophic cardiovascular event.
What We Measure
The standard lipid panel, including the LDL-cholesterol, triglycerides, and total cholesterol, is a good “back-of-the-envelope” way of determining the amounts and types of lipids you have circulating in your body, as a surrogate marker for heart health risk.
But if you look back at people who have had heart attacks and strokes, and ask how many had high LDL-cholesterol, the answer isn’t 100%. There are some people using the standard detection methods, who do not have a measured high LDL-cholesterol, but who have had a bad outcome.
As a result, we need better methods to screen patients and ensure we’re identifying those who can benefit from earlier treatment, whether through lifestyle or medications.
The ApoB, or Apolipoprotein B, is one of those methods. Since there is one ApoB protein on each LDL particle (as well as on each IDL or VLDL), by measuring the ApoB, we’re essentially doing a head count of all the atherogenic particles in the bloodstream. A value of >90 mg/dL is considered a positive test (but ideally we would want this lower than the lab threshold).
This matters because when looking for heart disease, the LDL-cholesterol by itself doesn’t paint the whole picture.
How to Interpret ApoB
Let’s imagine that you’re standing on a shoreline. This beach represents your arteries. Out to sea and headed your way is an enemy naval fleet, looking to fire cannons on your beach. The sailors are the cholesterol, and each is housed in a ship, the LDL particle. (Since the cholesterol is inside the LDL particle, we’ll call the sailors “LDL-cholesterol”).
While you don’t want too many sailors on your waters, knowing the number of ships in crucial in weighing your risk of a full scale invasion. A single fully-staffed ship has one risk profile, while a skeleton crew operating a complete armada surrounding you has another.
So how do we count the number of ships? The ApoB. The ApoB is like the flag on each ship, and since each LDL particle has only one ApoB, by counting the number of flags, we’re also essentially counting the number of vessels.
By using these two pieces of information together, we can get a sense of your cardiac risk profile, and where diet and exercise versus medications come into play when designing a long term plan for your health.
A Focus on Prevention
While the data for using ApoB are certainly well documented in medical literature, I imagine it will take a few more years gain widespread adoption. Medicine can be very consensus-based, and until these newer tests are widely published in guidelines, some physicians will hesitate to order them. Previous concerns about cost, though, have fallen by the wayside; as detection methods have improved, the price of this test has also declined significantly, and it’s readily available in most labs.
If the goal is prevention, we should be using every reasonable tool we have available to find out what risk factors you have. High cholesterol is too common a disease with too serious a consequence to do otherwise.
The sooner we know and make a plan, the easier it will be to change the outcome.