Coronary Artery Disease, Calcium Scores, and Surgery
Coronary Artery Disease, Calcium Scores, and Surgery
Should we be operating on everyone with coronary artery disease?
Background
For many years I have been studying and contemplating the nature of vascular disease. The circulatory system has been a fascination since beginning this career.
It’s hard to explain why. For starters, the heart is so alive. Constantly beating - from birth til death. Without rest.
God forbid it take a break. If it did…we would start pounding the chest, injecting IV drugs or electrocuting it.
Then, you have the arteries and vessels. A road to every organ and body part. There are few modern aspects of medicine which are truly unique - one of these are minimally invasive intra-vascular surgeries. Professionally referred to as interventional radiology.
Despite this fascination, life ultimately led me to a different path. One in which I am always studying and diagnosing vascular disease, without intervention.
So, I will caveat the following analysis with this.
I am not a cardiologist nor a cardiothoracic surgeon. In some ways, this is a good thing. In others, it’s not. You be the judge.
Coronary Artery Disease
If you are an avid consumer of the digital health space, you will have noticed discussions about coronary artery disease, coronary calcium scores, and atherosclerosis.
This has become a particularly common point of discussion among both cardiologists for risk-stratification, and among low-carb/ketogenic/carnivore diet fanatics.
On the one hand, cardiologists pursue aggressive therapies for people with high calcium scores…and on the other, diet fanatics think they are healthy because their calcium score is low.
In my opinion, both of these views are misguided.
Why?
For starters, just because your arteries are mineralized (or calcified) does not mean they are obstructed. But, if they are mineralized and obstructed…it has a different significance.
Mineralization/calcification is a rather long-term process. Which means that if your arteries have slowly calcified and obstructed, but you haven’t noticed…the organ has collateral blood supply. This collateral supply can come from old vessels that have re-opened (usually congenital dormant tiny vessels). Or, the chronic state of oxygen-deprivation has signaled the proliferation of new vessels.
What this means is that the chronically obstructed vessels need not be re-opened. Because the organ already has another route by which it receives blood. This is typically called collateral supply.
On the flip side, just because your arteries have no calcification…does not mean they do not contain soft-plaque or undergone remodeling such that healthy laminar flow can be disrupted.
A good example of this are carotid webs.
Despite the fact that there is no atherosclerotic plaque at the location of the web, this ridge creates a zone of low-flow in which blood can become static and form clots. Which can then travel up the artery into the brain and cause a stroke.
As you can see, the problem of atherosclerosis and cardiovascular disease is not as cut-and-dry as most doctors and cardiologists make it out to seem.
Public Health Campaigns
If you live in a major north american city, you may have encountered public health campaigns.
These campaigns often take the form of promoting screening programs for various illnesses, such as cancer and heart disease.
What may seem like a well-intended attempt to improve public health, has less-than-benign practical consequences.
One of these consequences is that people who are otherwise asymptomatic or without clinical illness, will be lead down a path of testing and treatment which can result in harm they could have otherwise avoided.
Let me give you an example to illustrate what I mean.
Heart Disease & Calcium Scores
Take for example the recent rise in campaigns for being “heart healthy.”
Campaigns that are funded and organized by the very same organizations and institutions which have been “treating” heart disease for the last 50 years…all the while, the rates of heart disease and mortality continue to rise.
What does this program look like?
Well, you might find yourself in a community clinic in which someone promotes things like a lipid panel (to check your cholesterol) or a coronary calcium CT scan to check for atherosclerosis.
Coronary calcium seems to be all the rage today, both within the mainstream medical establishment as well as the alternative health space. Essentially, this is a test that gives an estimate of calcification burden along your coronary arteries. Based on the volume of calcification, you are given a risk score.
People tend to believe it gives them some indicator of their risk for future cardiovascular events (such as heart attack or stroke). To some extent, it does. However, this is not the only predictor of future cardiac risk…and taken as a factor on its own, it is of limited utility.
For example, let’s say you have a high calcium score. But, you have no other comorbidities such as diabetes, hypertension, prior cardiovascular events, and so on. You don’t even have any history of chest pain, or cardiac symptoms. No history of alcohol abuse or smoking cigarettes (which are huge risk factors). Just the calcium. What are you supposed to do with this high calcium score?
Should you undergo a surgery to revascularize the heart?
You see, almost all interventions have been initially designed and studied for secondary prevention - that is, to prevent a cardiovascular event from happening again.
In fact, the strongest case that can be made for statin use (if indeed there is ever a need to take a statin), is for secondary prevention.
But, what about surgery?
Should you, in the above example, undergo cardiac catheterization or open heart surgery?
This is where things get very messy.
Because, to this day, the case for surgical intervention versus conservative therapy (i.e. prescription drugs and lifestyle modification) is not as strong as people would believe. Take this recent meta-analysis hoping to elucidate an answer to this question in people with stable coronary disease.
Keep in mind, the clinical trials included in this meta-analysis did not include a patient population identical to the scenario I described above. In fact, many of these trials included patients with several other risk factors - as you would expect from a clinical trial.
Remember this while reading through their results. The patient population of these trials were far higher risk than the example we outlined above. Many of them have a history of prior stroke or heart attack, almost a third of them are smokers or have diabetes. More than half have hypertension, and so on.
As far as the cardiology community is concerned, these results are the best case justification for therapy. So, let’s dig into the results of this meta-analysis.
First up, all-cause mortality.
There was no significant difference in all-cause mortality between patients who underwent some sort of surgery or who received medical therapy (e.g. prescription drugs).
What about cardiovascular outcomes? The case for revascularization looks somewhat more convincing. Despite the fact that some of these studies have equivocal findings, on average there is a statistically significant (though marginal) benefit observed across thousands of patients.
You could make the case that the data above is more than enough to convince you of the value of surgical intervention.
However, there is a very important distinction you must account for. Almost all of these clinical trials are performed on people with a history of cardiovascular stress in some form or another. This includes:
Hypertension and heart failure
Angina, aka bouts of chest pain
Prior ischemic events
Prior major cardiovascular events: strokes and heart attacks
Compare this with the population of people undergoing screening at community events. By and large, these people have very few of the above in their history…that’s why they are undergoing screening tests. If they already had the problems of those in the clinical trials, they would be way past screening.
Is It Worth It?
To answer this question, let’s return to a concept mentioned earlier.
Primary prevention involves trying to prevent a first episode of a disease.
Secondary prevention involves trying to prevent a repeat episode of a disease. Almost all of our surgical interventions have robust data for secondary prevention.
If you are undergoing screening tests, then by definition you are in the category of primary prevention.
Thus, whatever intervention you are considering…you want it to prevent a first episode.
What if I were to tell you that these interventions, including percutaneous (minimally invasive) or open-heart surgery have risks and complications?
Complications like:
Arrhythmias like Atrial Fibrillation which can lead to worsening cardiac dysfunction, strokes, and heart attacks
Embolism of clots, which can lead to strokes
Direct damage to the heart or blood vessels, leading to vasospasm or dissection
The rates of these complications are non-trivial, and depending on your particular circumstance may outweigh any benefit you may obtain from the procedure.
Strokes (brain infarcts) are one of the few complications which cannot be brushed aside as an “expected change” associated with heart surgery. After all, if you open up the chest, touch the heart and vessels…some of these “complications” can get categorized as “expected changes" - a term famously used in radiology reporting.
But, if you are operating on the chest…and the patient gets a stroke…that’s harder to mask in the data.
As you can see, the strokes in the same clinical trials favor conservative medical therapy over the surgeries.
I ask you:
What would be the point of undergoing a surgery in hopes to prevent the very thing which can occur as a complication of the surgery itself?
Even if your calcium score is high, your chances of a major cardiovascular event are more or less similar to the likelihood of experiencing one out of a number of complications associated with the surgeries.
If you want to hear my thoughts on atherosclerosis, heart disease, and the myth of vulnerable coronary artery plaques, check out this podcast episode:
Cut off your breasts.
Yank out your prostate.
Grab a double bypass and get half off a colostomy bag with this month's special!
Carve-outs, amputations and removals: Big Medical's version of preventive medicine.
thanks again for another great article breaking down the various notions about coronary artery plaque, heart disease and risks of serious events. You have a real gift for synthesizing a complex body of information and delivering it to your readers in a very accessible way.
My understanding of the development of coronary artery plaque is that we 'lay down' plaque along vessel walls to heal micro-tears in the endothelium. The micro-tears are the result of inflammation, the biggest offender being high consumption of simple sugars in the diet. I am sure other dietary and environmental contributors play a big role (highly processed foods, inferior water, toxins in our food, water and air, etc).
My understanding of the association between high circulating serum cholesterol levels and coronary artery disease was really challenged when my father-in-law (in his mid 60's at the time) developed idiopathic cardiomyopathy and needed a heart transplant. He had been on Mevacor for years for high serum cholesterol. A medical center in Austin, Tx, where I live, agreed to do a heart transplant from an older donor provided his coronary arteries looked good. He had serum cholesterols in the mid-to high 300's. A heart cath showed his vessels were 100% clear and he underwent a heart transplant with great success. At the same time an uncle (also a physician) was grounded from flying his plane due to high serum cholesterols. He went on a seriously crazy low-fat diet and got his serum cholesterol down to 70. A heart cath showed he had serous cardiovascular disease with areas of occlusion. My theory was the diet caused massive inflammation likely the result of his high carb low fat diet which promoted plaque formation.
The history of how dietary fat became our enemy is a very interesting one and unsurprisingly fraught with corruption and interference from the food industry.