I have had numerous requests from doctors, patients and my readers for a thorough explanation of heart scans and their significance. In an effort to appease both sides of the exam table, I have written this post with enough depth to inform clinicians and hopefully enough explanation to educate non-physicians about the role and interpretation of some of these tests. In addition to learning about these important tests, you will also learn about common tools to assess heart disease risk and you will gain a deeper understanding of the root cause for heart disease, still the #1 killer in men and women.
I will also discuss the role of stress tests since there is often confusion on the part of patients and doctors about what the role is of stress tests vs heart scans. Do keep in mind that the decision regarding which test you should get is often complex and should be done in partnership with your doctor. There are risks and benefits to each of the tests which we'll discuss towards the end.
What is the Heart Scan?
First let's talk about semantics. The word “heart scan” is often used synonymously with terms such as EBCT (Electron Beam CT) or Coronary Calcium Scan. You are likely familiar with a form of x-ray testing called the CT (Computerized Tomography) Scan, which is still sometimes referred to as a “CAT Scan.” A “Heart Scan” is a similar test that is focused on imaging the heart, and specifically the arteries that feed and nourish the heart, which we refer to as the coronary arteries. I will be using the term “EBCT” throughout this post to indicate a CT scan of the heart that measures calcium (see next section) to help assess plaque.
There is a variation of this test called Coronary CTA (CT Angiography) or “CCTA” or just “CTA,” which I'll explain at the end, but most of this post will be focused on the EBCT (Coronary Calcium Scan) since that is the more commonly used test to screen individuals without symptoms for plaque.
Since the CTA involves injecting contrast, we often refer to this as a “wet heart scan,” while the EBCT, which does not involve contrast is nicknamed a “dry heart scan.” Let's summarize:
EBCT (Electron Beam CT or Coronary Calcium Scan): “Dry scan” without contrast or injectable drugs. Most common heart imaging study done in individuals without symptoms. Provides you with a calcium score. This post will mostly focus on this test.
CTA (CT Angiography) or CCTA (Coronary CT Angiography): “Wet scan” since you inject contrast and also have to inject additional medications for the test. This study can be done in individuals with or without symptoms. I will discuss this test in a separate section at the end.
The Significance of Calcium
The use of calcium to detect and measure heart-attack causing plaques is a point of confusion. I've had patients ask me if they should stop drinking milk since they think calcium “causes” plaque formation. To be accurate, calcium is one of many ingredients involved in the evolution and formation of plaques.
In fact, calcium is involved in the healing of plaques, like scar tissue helps heal a wound on your skin. This can complicate the interpretation of follow-up heart scans since an increased score may signify healing, rather than progression of disease. We will discuss this further later.
Let's go over a few key concepts and terms first, which will help you better understand this post:
Coronary arteries: the specific blood vessels that feed and nourish the heart (image below).
Coronary artery disease (aka CAD) is a narrowing in the coronary arteries most commonly caused by plaques, that leads to a heart attack or angina (chest pain and/or shortness of breath due to narrowing in the arteries).
Atherosclerosis is the actual process that leads to formation of artery-narrowing plaques, resulting in coronary artery disease. This process starts in childhood, so healthy lifestyle must start from the beginning of life!
Wall Injury: The inciting event for atherosclerosis is injury to the inner lining of the blood vessel wall (aka “endothelial cell lining”), which can result from multiple factors (high blood pressure, diabetes, smoking, chronic stress, toxins, etc.). The “injury” is a silent event which you will not feel, but over the years leads to an ongoing cascade of events culminating in the formation of a plaque.
Plaque Rupture: Heart attacks occur when the plaque at the blood vessel wall ruptures and completely blocks off one or more coronary arteries.
Calcium is one of many ingredients found in plaques and is used as a marker to detect plaques. One of calcium's roles is to heal and stabilize the plaque to prevent rupture.
Soft Plaques: These are plaques that do not contain calcium and so would not be seen on an EBCT (coronary calcium scan). Soft plaques are actually more dangerous than those that contain calcium. I'll discuss this later in the post.
I want you to read this list over and over until the terms and concepts are solid. I sometimes use the analogy of a volcano to explain the above steps. Atherosclerosis is the process that forms the volcano (plaque), but the volcano itself may not cause immediate harm unless it's so massive that it's reducing blood flow.
More commonly you get smaller volcanoes (plaques) which are not compromising blood flow, but when the volcano erupts (plaque rupture), you get serious damage (heart attack).
The lava that comes out of the volcano is the erupting blood clot that spews out of the volcanic plaque and closes off the coronary arterie(s).
The image below shows this perfectly. The leftmost image is of the heart with the superimposed lacy network of coronary arteries (recall definition above) that feed and oxygenate it. Right of the picture of the heart are 3 close-up views of a specific major coronary artery called the LAD (left anterior descending). Notice how the blood is flowing from north to south (signified by the blue arrow), and how the LAD has been sliced open so we can see exactly what's happening inside this key coronary artery.
The yellow mountainous structure next to the arrow is the volcanic plaque which has a fibrous cap lying over it like a seal to help prevent rupture. I'm going to use the word volcano and plaque interchangeably. The middle image shows the cap rupture, which is an event we refer to as “plaque rupture.” The image to the right shows how a blood clot erupts from the plaque directly into the opening of the blood vessel, just like a volcano spewing out lava.
Now the blood vessel is completely blocked off and the blood flow (blue arrow) cannot travel south. As a result, the region of the heart muscle that depends on this specific blood vessel to nourish it, will be starved of oxygen and nutrition and will die. This is what we refer to as a heart attack or medical jargon calls it a “myocardial infarction,” abbreviated MI. Infarction means death of a tissue (in this case the heart muscle) due to a lack of blood supply.
Since calcium is one of the building blocks of the plaque, it serves as a marker for the presence of the plaque. The presence of calcium tells us a plaque (volcano) is present and the higher the score, the greater the size of the volcano. Keep in mind that volcanoes come in all shapes and sizes. A small volcano would register a lower calcium score, but it still has the potential to erupt and block off the blood vessel, causing a heart attack. Some plaques are sneaky and don't contain detectable calcium. We call these “soft plaques” and these are especially prone to rupture, but since they lack calcium, would register a zero calcium score on your EBCT.
Soft volcanoes (lack calcium) are generally more dangerous than hard ones since recall we talked about how the calcium helps to solidify the volcano and reduce the risk of rupture (eruption).
That's why sometimes an increase in your calcium score over time may actually be a sign of the plaque healing rather than getting worse. I'll discuss soft plaques in more detail later in this post.
Interpreting Calcium Scores
Now that you understand heart scans and the process leading to heart attacks, let's move onto the business of understanding those calcium scores that appear on your EBCT report. Typical reference ranges are below. Reminder again that atherosclerosis is the condition/disease that produces the plaque.
0 No atherosclerosis (plaque)-does not rule out “soft plaque” (see next section)
1-99 Mild atherosclerosis (plaque)
100-399 Moderate atherosclerosis (plaque)
>400 Severe atherosclerosis (plaque)
The absolute score itself provides important, but limited information. Having a score of 100 indicates a much higher risk in a 30 year old vs a 75 year old. The reason is because as we age, we expect that some degree of atherosclerosis naturally may occur. To put these scores in context, we need to include background factors such as your age, ethnicity, and gender, which are incorporated into the MESA calculator. If you've had a calcium scan done before, click on the link and enter your age, gender and ethnicity.
If you are Asian Indian, choose “white” as your ethnicity since initial results from the MASALA study suggest that South Asians have a similar incidence of coronary calcium as Caucasians, although the incidence of coronary artery disease in South Asians is actually higher. Below is an example used for a 48 year old white male with a calcium score of 100. The first result listed is 35%, which is the probability of a non-zero score in this specific group (white male).
The more important number is below that 35%, where it says “the observed calcium score is this initial percentile of 35% and is listed as this individual being in the 91st percentile for a score of 100. That is the number you need to pay attention to. The higher the percentile number the greater the risk. Generally if you're above the 75th%, a statin would be indicated, as in this specific example. The decision to start a statin is not always straightforward and needs to be discussed with your doctor.
Beware of Soft Plaques and Celebrating After a Zero Calcium Score
Soft plaques (aka non-calcified plaques) do not contain calcium and thus don't show up on a regular EBCT test. Don't be fooled by the word “soft.” These plaques are actually more dangerous and prone to rupture than the calcified ones that show up on the EBCT. Recall I said the calcium is like a protective sealant that stabilizes the plaque and reduces, but does not eliminate, rupture risk.
What increases the risk of developing these volatile soft plaques? Calcium typically appears in older, more mature plaques. As a result, younger individuals with a family history of early heart disease can be at higher risk of having these soft plaques as shown in this study which makes the following conclusion:
“Apparently healthy men and women from families with early onset CAD (coronary artery disease) have a high prevalence of subclinical CAD, composed primarily of noncalcified (soft) plaque.”
What about if you're young and diabetic? Diabetes has the effect of accelerating plaque formation and overall heart disease earlier in life, so there is a greater risk you may develop these dangerous soft plaques. This study found that 35% of diabetics less than age 40 had soft plaque. In my clinical practice I see quite a few South Asians who have a family history of early heart disease AND diabetes, which presumably would further increase the risk of having a volatile soft plaque that would be undetectable on a regular coronary calcium scan.
The final lifestyle habit that raises the risk of developing these dangerous soft plaques that go under the radar of a routine coronary calcium scan is smoking.
Smoking significantly raises the risk of soft plaques, mixed plaques (soft and hard components), and overall atherosclerosis in general.
Smoking continues to be the number one reversible risk factor for heart disease and even occasional social smoking can be enough to destabilize plaques.
How to Stabilize Plaques and Tame the Volcano
Before we talk about CTA, I thought I'd give you a lifestyle break since all this talk about plaques might make you a little nervous. I see lots of patients in my clinic who have plaque and often they develop a case of what I call “plaqeuophobia,” where they have tremendous anxiety about the plaque growing inside their blood vessels to obstruct blood flow completely or erupting into a life-ending heart attack.
Let me provide a little perspective here now that you have a deeper understanding of how plaques develop. Many patients tell me “how do I make that plaque disappear?” The more realistic goal is actually to stabilize the plaque or what I call “tame the volcano.” No one can see your plaque and judge you based on how your plaque looks, so all you care about is making sure that volcano (plaque) doesn't become unstable and erupt. See the image below which is a cross-sectional view of your blood vessel, meaning you are looking inside the blood vessel head on like looking into a straw.
On the left you have a normal artery, in the middle you have an unstable or “vulnerable” plaque and on the right you have a “stable” plaque. The red circle is the opening of the blood vessel. I agree that the normal plaque is the best scenario, but the “stable” plaque can also lead to a great outcome. When you look at the middle image, there are a few items that make this plaque vulnerable.
First, there are lots of immune system cells like macrophages and lymphocytes. Anything in your lifestyle that causes chronic activation of your immune system or what we've referred to as “inflammation,” will destabilize your plaque over time.
There is also something labeled the “fibrous cap,” which we can think of as a lid on top of your volcano. If the lid is thin and weak, it will crack and your volcano will erupt. If the lid is thick and strong (“thick fibrous cap”), it will help keep your plaque dormant.
Now notice all the items listed under the transition arrow where you go from stable to unstable. This is a partial list of some of the chemicals and processes that when optimized can help stabilize the plaque. As we've discussed repeatedly in the past you want to do everything possible to tame inflammation and reduce or ideally reverse insulin resistance to prevent a new volcano from forming or an existing volcano from erupting.
This means eating an anti-oxidant rich, anti-inflammatory diet, getting regular exercise, and managing stress and sleep. All messages you've heard from me before, but I'm hoping the added knowledge of how plaques form, destabilize, and cause destruction might be an additional motivator. At the end of the post I highlight the profound impact of chronic stress and sleep deprivation on plaque disruption. Many of you reading this post keep improving diet and adding more exercise which is ok to a certain point, but refuse to acknowledge how unbelievably destabilizing chronic stress is.
Chronic stress activates the immune system so those macrophages and lymphocytes infiltrate the plaque to make it more vulnerable. The stress can be very subtle and can be non-angry stress where you look calm on the outside but you are completely overscheduled and can barely sit still for a few minutes. These are the families I see repeatedly in my clinic who don't realize the adverse impact of stress on the development of heart disease. Be sure to check out my stress resources post here.
I also want to take this opportunity to emphasize how exercise, done the right way (read my post here), has some of the most dramatic impacts on remodeling your coronary arteries in ways that will prevent your plaque from becoming unstable. Exercise relaxes the blood vessels and makes them more resilient, it lowers inflammation, and it helps reverse insulin resistance.
If you deliberately want your volcano to erupt, the easiest way to accomplish that goal is to spend most of your day sitting and neglecting regular exercise, hurrying, worrying, eating unhealthy foods and compromising sleep.
Ok…I hope I made my point clear…now back to heart testing.
What about the CTA?
Let's now talk about the CT Angiogram (CTA or CCTA) test which is different than the EBCT we have been discussing thus far. A CTA provides a higher resolution image of the coronary arteries and involves injecting contrast, a drug to slow the heart down, and a drug to open up the coronary arteries.
Unlike the EBCT, the benefit of the CTA is it can visualize those sneaky, dangerous soft plaques.
In fact it's so good that if your CTA is negative, we can be 97-99% sure you don't have plaque in your coronary arteries and we can say with a great degree of certainty that you won't die from a heart attack in the next 7 years.
So why don't we just do a CTA instead of an EBCT in at-risk individuals since it's more accurate and can detect dangerous soft plaques? Let's discuss that next.
Risks of EBCT and CTA
The EBCT is a simple test that just takes minutes and the cost is also reasonable. The primary risk is exposure to radiation but the amount (measured in mSv) is only about 0.9 mSv whereas annual background radiation exposure from the environment is around 3mSv. The CTA exposes you to slightly more radiation at 2-3 mSv in addition to risks associated with the injectable agents (contrast and medications). It is also more costly than EBCT.
In both cases another often overlooked risk which prevents doctors from ordering these tests on everyone is the risk of detecting nodules or other mostly harmless findings on your CT scan, which can be found in your lung or elsewhere. Despite these being common in healthy humans, once we find them, often we have to order repeat tests to monitor them (more radiation exposure) and in some cases these tests may lead to more invasive procedures like a biopsy.
Serial (Repeat) Heart Scans
Many of my patients who get heart scan tests done often ask me when they can get their next one. This is a controversial area. As I mentioned previously, if you had calcium in your arteries already, an increase in your score on a repeat test may be good (more calcium to stabilize the plaque and prevent rupture), bad (overall plaque size has gotten larger and possibly more unstable) or neutral.
More recent studies seem to indicate that rather than assess the progression of the calcium and then estimate the risk based on this increase, it's simpler and just as accurate to base risk on your most recent calcium score. So if you had an initial calcium score of 50 and then another 5 years later of 100, you would independently assess your risk based on the score of 100 (more recent test) and can use the MESA calculator we discussed earlier. Dr.PK Shah, an esteemed cardiologist, provides a nice summary of this approach to serial EBCTs here.
Keep in mind that newer generation heart scan tests are getting better at evaluating specific characteristics of the plaque that may indicate higher risk. The field of heart imaging is growing more and more promising with higher resolution scanners that continue to reduce radiation exposure.
Comparing Heart Scans to Stress Tests
Heart scans are an anatomic test that provide a static image of the arteries and of any existing plaque. Stress tests are a functional test which provides more dynamic information while the patient is put under some form of “stress” to raise their heart rate.
Just like the name implies, a stress test involves 2 components: a “stress” and a “test.” The stress we are referring to is a stimulus that challenges the heart to perform at a level above its resting state. For individuals who can exercise, making them run on a treadmill is the preferred stressor since it mimics real life. For those who can't exercise, a drug is injected that can raise heart rate and partially mimic the effects of exercise on the heart.
The second component of the stress test is the test, which evaluates the performance of the heart under the conditions of the stressor (exercise or injected drug). The test can be an EKG (electrical performance of the heart), an ultrasound or “echo” (visualizes the heart's motion), or a nuclear scan where a radioactive tracer is injected into the blood to evaluate areas of viable heart muscle. Your doctor will decide which combination of stress (exercise vs drug) and test (EKG, echo, nuclear scan) is right for you.
Now are the heart scan and stress tests interchangeable? In other words, if I have a “normal” stress test, does that mean my heart is free of danger and a heart scan would provide no additional value? Unfortunately not. A stress test simply detects if there is any narrowing in your blood vessel during the stress which would manifest as a change in your test (EKG abnormality, echo abnormality, perfusion defect on scan), usually accompanied by you having symptoms (chest pain and/or shortness of breath), although some individuals may have no perceptible symptoms.
However, you can have a normal stress test today and drop dead from a heart attack tomorrow.
How is that possible? When a plaque develops over time, your blood vessel can remodel. The plaque can actually grow into the wall of the blood vessel instead of towards the opening, meaning it won't cause narrowing in the blood vessel. The volcanic plaque literally goes underground and out of the way from the opening of the artery so blood can freely flow. This is an adaptation that allows you to exercise effortlessly at high loads.
Ever heard of a runner or athlete who was in incredible shape but dropped dead from a heart attack? In this case the athlete likely had adaptive remodeling in his/her blood vessel that stashed the plaque away into the thin wall of the vessel while keeping the lumen (opening) of the tube intact so blood flow isn't compromised. However, hiding the plaque in the blood vessel wall doesn't eliminate risk. The volcano is still there and it can erupt any moment to close off the blood vessel within seconds.
Unlike the stress test, the heart scan is a “volcano-detector.” It images the plaque in the arteries. It doesn't give us any functional information about whether the blood flow to the heart is compromised during exercise, but it can at least tell us plaque is present and quantify its size using the calcium score.
Now can someone with a zero calcium score have an abnormal stress test? The answer is yes. It's not common, but recall how we previously mentioned those “soft plaques” that lack detectable calcium, but are especially vulnerable to rupture.
In summary, heart scans and stress tests provide different types of information. Heart scans provide a snapshot of whether plaque is present, where it's present and how much is present. Stress tests tell you if the plaque is actually narrowing the blood vessel under “stress” (exercise or an injected drug that stresses your heart if you can't exercise).
Together, both tests give you a fuller assessment of heart anatomy and function, but you don't need to get both in all individuals. It depends on each individual case. Let's now discuss some general approaches to common situations.
Assess Your Heart Disease Risk First
We covered a lot of information, so we'll simplify into a few common scenarios. Before we do that, you need to understand which risk category you fall into. Online risk calculators like the ASCVD Risk estimator can help put you in a risk category. I personally don't use the risk calculators much. If they classify you as intermediate to high risk, that's worth paying attention to. If they put you at low risk, be a little skeptical.
I often find risk calculators tend to underestimate heart disease risk and they do not incorporate key lifestyle risk factors such as stress and sleep or a thorough evaluation for insulin resistance using markers like triglycerides and waist circumference.
Below is a classic example of a 38 year old patient who saw me after a heart attack and was told by his prior doctor that he was “low risk” based on the ASCVD calculator. No fault of the doctor who followed standard guidelines for heart disease risk assessment.
See his results below. I had to enter “40” for the age since the calculator won't accept an age below 40. The 10 year risk assessment based on this person's results was only 1.5%, putting him in the low risk category. Despite this, he had a massive heart attack at 38.
I've seen plenty of heart disease patients like this whose pre-heart attack risk scores ranked them as “low risk.” To understand why he had a heart attack, you'd have to look at all of the gaps in this risk tool. Below are some of the risk factors that were not assessed for by this tool which together contributed to his heart attack:
Increased waist circumference
Sedentary lifestyle (cardiovascular deconditioning is a major risk for heart disease)
Chronic stress from work (busy start-up) and personal (marital issues)
Sleep deprivation (average bedtime between 1-2a)
Elevated hsCRP (inflammation test) of 8.5 (I check in select patients)
Family history of early heart disease
You can see how the ASCVD Risk calculator misses so many critical risk factors. In addition, despite metabolic syndrome/insulin resistance being a major global cause for heart disease, this calculator just asks if you are diabetic or not.
The majority of insulin resistant heart disease I see in my clinic happens in non-diabetics who have preceding metabolic syndrome which is missed by common risk calculators.
The so-called “low risk” heart attack patient mentioned above had metabolic syndrome. Read my very popular post on insulin resistance/metabolic syndrome here if you are not familiar with these terms.
If you've had a calcium score done in the past, using the MESA 10 year risk calculator found here provides a better risk assessment than the ASCVD estimator since it allows you to add your calcium score and also takes into consideration family history. I would still be cautious about “low risk” patients since this calculator still misses many of the key lifestyle factors I mentioned above. My wellness program teaches you about using various tools for assessing heart disease and insulin resistant risk, in addition to providing animations that simplify these concepts.
Getting a heart scan at either extreme of age doesn't make sense for most individuals. Generally it is said that if you are less than age 40, a coronary calcium scan is not useful since you are likely too young to develop calcified arteries. Although I do broadly agree with this statement, we do have to assess the impact of the prolonged exposure risk of modern life.
What I mean by this is the fact that today's generation of children are more sedentary and unhealthy than any that have preceded them.
A child's modern day exposure to insulin resistance and obesity starts much earlier and potentially may accelerate the onset of atherosclerosis.
In fact, insulin resistance for some individuals started in utero since they were born to mothers with gestational diabetes. When I hear about this earlier onset of risk exposure, I may consider getting a heart scan at a younger age and I have had cases of detectable coronary calcium in patients as young as late 20s to early 30s.
Even if their scans detected no calcium, recall that the risk of non-calcified soft plaque in younger individuals is still quite high, especially if you also layer on the 3 risks for soft plaque we discussed: family history, diabetes/insulin resistance, smoking.
On the other end of the spectrum are the elderly. Developing calcium in the arteries is a common consequence of aging, so if you are above age 70-75, a heart scan may not provide much value since you likely have calcium already. The MESA calculator we discussed earlier will still provide a risk percentile based on your age to provide context, but I'm generally less motivated to get a heart scan in the elderly if there are no other indications.
Now back to some common scenarios:
No Symptoms and Low to No Risk
If your risk is low, you don't need heart imaging. Be sure to continue monitoring your risk with tests like a full lipid panel, blood glucose, blood pressure, and body metrics (emphasize waistline over weight-refer to my body size post). If you get bumped up in risk category based on these tests and/or your family history, then imaging might be necessary.
No Symptoms and Intermediate Risk
Intermediate risk is really the sweet spot for when we consider doing heart scans to help us shift from indecisiveness to a clearer treatment plan. If your doctor agrees you are intermediate risk or in that “gray zone” where you're discussing whether cholesterol medications like statins are indicated, then a heart scan may help you both make a decision on whether medications make sense.
A zero or low calcium score may help drop someone from intermediate risk to low risk. If your calcium score is generally above the 75th percentile, then statins are typically indicated. Again, discuss this with your doctor and always remember that zero calcium does not mean zero plaque. Refer back to our prior discussions on soft plaque.
No Symptoms and High Risk
If you are in a high heart disease risk category, then the heart scan actually becomes a less useful test. That's because the decision to start medications and aggressively modify lifestyle is clear, regardless of the heart scan result. In my less motivated patients I may still get the heart scan or a CTA as an additional visual data point to assess the coronary arteries. It's also a huge motivator for high risk patients to actually see visible plaque in their arteries rather than me verbally tell them they are high risk based on my clinical assessment or a risk calculator score.
If you have symptoms that suggest coronary artery disease, then an EBCT would not be the first test to order. An EKG is always the first test and if there are concerning changes, you would be referred urgently for a further work-up. If your EKG is normal, you would likely be referred for some type of stress test.
Again, to repeat, an EBCT is not a test we do for individuals with symptoms like chest pain.
Now let me test you to see if you've been paying attention. If your stress test is normal, does it mean you definitely have no plaque? Absolutely not. Remember again that the stress test is simply assessing if your coronary arteries are narrowed during “stress” (exercise or injected medications). You might still have a plaque that is hiding in the blood vessel wall, but not compromising blood flow in the artery.
I have had numerous patients over the years with perfectly normal stress tests, but given their intermediate to high risk, we still got a heart scan which showed the presence of plaque. Having plaque is a powerful motivator for individuals to prioritize lifestyle, and a strong indication to start medications like statins.
Now although I mentioned that EBCT is not appropriate to do in patients with symptoms, a CTA actually is a good test to do in individuals with possible heart symptoms. Although in the United States stress tests are done more routinely as a first line evaluation for cardiac symptoms, in the UK they use CTA first.
Studies support the UK's CTA first approach and this study shows that diabetics with chest pain who got CTA first compared to those who got a stress test had a lower incidence of heart attacks and heart attack related deaths. At some point in the future, the US may also change their guidelines to a CT-first approach and many cardiologists are already using it first line. The ER is another place where CTAs are often done to evaluate chest pain since in addition to accurately assessing the coronary arteries, you can also rule out other serious conditions (pulmonary embolism, aortic dissection, etc.).
I know this was a detailed post and my intent was not to confuse you, but rather to explain what a complex task it is to assess heart disease risk in each individual. As you've learned from this post, risk calculators are highly imperfect and we still don't have a 100% accurate test that is completely risk-free. This means you need to work with your doctor on a rationale approach to understanding your individual risk and what sorts of tests make the most sense (if any).
An evaluation for heart disease risk is not an opportunity for you to find an excuse to continue your current lifestyle, unless it's truly impeccable. For example, a zero calcium score doesn't mean you can continue sitting all day and eating junk. Heart disease is the #1 killer, but there are a long list of other chronic health conditions that can lead to death and disability.
I also wanted you to understand that there is virtually no scenario where I see patients and tell them you are absolutely out of the woods when it comes to heart disease risk. I have been surprised, shocked and mystified by individuals who I thought had little to no chance of developing a heart attack, who went onto have one.
I'm seeing a growing number of heart attacks due predominantly to what I think are cases of chronic stress and sleep deprivation. I blogged on this a while ago here, where I discuss a case study of a Silicon Valley executive with heart disease. These are not isolated cases and I've seen enough supportive research in combination with my clinical experience to motivate me to do everything I can to prioritize stress and sleep in my own life, and motivate my patients to do the same. Again, check out my dedicated stress post with listed resources here.
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