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Coronary calcium score hidden risks

Severe Coronary Artery Disease Despite a Calcium Score of Zero

Last Updated: July 27, 2023 | Dr Reza Moazzeni

Introduction: Why Coronary Calcium Scoring Isn't Always the Best Choice

Coronary calcium scoring has emerged recently as a popular, non-invasive test to assess an individual’s risk of a future heart attack. This screening tool measures the amount of calcium in the walls of the coronary arteries, a significant predictor of coronary artery disease (CAD). Despite its rising popularity and apparent simplicity, it’s crucial for both medical professionals and patients to understand the limitations of this test, as inappropriate use can lead to potentially serious consequences, including missed diagnoses or unnecessary anxiety.

We will focus on two patient groups in whom coronary calcium scoring may not be optimal: individuals already at high risk for coronary artery disease and patients with symptoms suggestive of CAD, such as chest pain.

Two Groups That Should Avoid Coronary Calcium Scoring

There are two groups of patients for whom coronary calcium scoring is not recommended:

  • Patients classified as “high-risk” for heart attack
  • Patients presenting with symptoms such as chest pain

To understand why coronary calcium scoring is not recommended for these groups, we need to examine “how risk is calculated” and the “causes of cardiac symptoms”.

Understanding ASCVD Risk and Risk Calculation for Heart Attack Prevention

Risk Factors and Primary Prevention

To calculate someone’s risk of future heart disease, factors such as age, gender, cholesterol levels, blood pressure, smoking status, and history of diabetes or heart disease are considered. These factors are entered into the ASCVD risk estimator plus calculator, which estimates the likelihood of experiencing a heart attack or stroke within the next 10 years. This calculator should only be used for primary prevention, meaning it is not for those with a history of heart attack, stent, bypass surgery, or known coronary artery disease based on imaging.

The Role of Calcium Scoring in Intermediate-risk patients

Calcium scoring can be helpful for those in the intermediate and low-risk categories. In the intermediate category, it can guide the intensity of therapy by nudging individuals towards either the low or high-risk groups. For example, a calcium score of zero might provide reassurance and allow for lifestyle changes before resorting to medications. However, a high score emphasizes the need for intensive medical therapy and lifestyle changes.

High-Risk Individuals and the Limitations of Calcium Scoring

For high-risk individuals with a risk estimate over 20%, calcium scoring is not beneficial. Regardless of the score, these individuals need intensive medical therapy, smoking cessation, and significant lifestyle changes to reduce their risk. A low calcium score should not be an excuse to ignore existing conditions like diabetes or hypertension, while a high score only reinforces the need for therapy and risk-factor management.

10-year risk of heart attack

The ASCVD calculator divides all individuals into three groups based on their cardiovascular risk levels: low-risk, intermediate-risk, and high-risk. The online tool calculates an individual’s 10-year risk of heart attack and stroke based on various factors. Those in the low-risk category have a risk of less than 5%, while those in the intermediate-risk category have a risk of 5-19%. The high-risk group has a risk of over 20%.

Proper diagnosis of an individual’s risk category helps doctors and patients make informed decisions about preventative measures and treatment options to maintain heart health.

Limitations of Online Risk Calculators and the Role of Calcium Scoring

For those in the low-risk group, it’s important to recognize the limitations of the ASCVD calculator. This online tool does not account for all risk factors, such as a strong family history of heart disease, high Lp(a), inflammatory diseases like rheumatoid arthritis, psoriasis, and lupus, as well as other factors like stress and a sedentary lifestyle. Consequently, someone with these risk factors might be incorrectly classified as “low-risk.”

Calcium scoring can be helpful in this situation. If a low-risk individual with unaccounted risk factors has a significantly elevated calcium score, it can indicate a higher risk level than initially assessed. This may warrant recategorization as high-risk and prompt the need for more aggressive treatment and lifestyle interventions.

The Causes of Cardiac Symptoms and Why Calcium Scoring Is Unsuitable

Calcium scoring is a valuable tool for assessing the risk of coronary artery disease (CAD), but it may not always be the most suitable diagnostic approach for all patients presenting with cardiac symptoms. There are several reasons for this:

Limited Detection of Plaque

Calcium scoring specifically measures the amount of calcified plaque within the coronary arteries, but it does not provide information about the presence of non-calcified or soft plaque. Soft plaques are more prone to rupture and can cause acute coronary events, such as heart attacks. Relying solely on calcium scoring may underestimate the risk of CAD in individuals with a predominance of non-calcified plaque.

Non-calcified plaque with calcium score zero
Coronary Calcium Score test can miss large plaques, if there is no calcium deposit within them.


Lack of Functional Assessment

Calcium scoring does not provide any insight into the functional status of the heart or the actual blood flow through the coronary arteries. It is possible for a person to have a high calcium score but still maintain adequate blood flow to the heart muscle, or vice versa. In such cases, additional diagnostic tests, such as stress testing or coronary angiography, may be required to assess the functional impact of the detected calcifications.

Non-Coronary Causes of Cardiac Symptoms

Cardiac symptoms can arise from various causes other than CAD. Relying on calcium scoring alone may not be sufficient to identify other potential causes, such as heart valve disorders, heart muscle abnormalities (cardiomyopathies), or electrical conduction issues (arrhythmias). In these situations, additional diagnostic tests, such as echocardiography or electrocardiography, may be necessary to pinpoint the underlying cause of the symptoms.

Not Suitable for All Patient Populations

Calcium scoring may not be the most appropriate diagnostic test for certain patient populations. In such cases, the risk of radiation exposure from the CT scan used in calcium scoring may outweigh the potential benefits of the test. Alternative non-invasive diagnostic tools, such as exercise stress testing, may be more suitable for these patients.

A Real-Life Example: Misuse of Coronary Calcium Scoring

Patient Background

37-year old with severe non-calcified plaque In our real-life example, we have a 37-year-old man who presented with shortness of breath and throat pain during exertion, symptoms that had been limiting his activities for the past three weeks. His medical history was significant for hypertension, high cholesterol, and prediabetes, which were not managed with medications. He was a non-smoker with no family history of heart attacks but had a sedentary lifestyle. His lab results showed high cholesterol and LDL levels, as well as an elevated HbA1C, indicative of diabetes. His blood pressure was high, and his BMI was 28, suggesting he was overweight.

Inappropriate Use of CT Calcium Score

Despite his symptoms and significant risk factors, a CT calcium score was ordered, which came back as zero. This result led to a false sense of reassurance that his risk of coronary artery disease was minimal. As we discussed earlier, a calcium score was not appropriate for this patient, considering his symptoms and his high-risk profile.

Further Evaluation and Discovery of Severe Blockage

Due to the persistence of his symptoms, he was referred for further evaluation. A stress echocardiogram was performed, revealing significant ischemia after only 4 minutes of exercise on a treadmill. This level of fitness was low for a 37-year-old man and indicated the presence of an underlying severe blockage in one of his main coronary arteries.

A subsequent CT coronary angiogram (CTCA) showed that the left anterior descending (LAD) artery was almost completely blocked, with only a tiny passage left for blood to flow through. There was no calcium detected in the plaque, which explained the zero calcium score. However, the severe blockage caused ischemia during exertion, leading to the patient’s symptoms.

Treatment and Resolution

Finally, an invasive coronary angiogram confirmed the near-total occlusion of the LAD artery. The blockage was successfully treated with a stent. Before the stenting procedure, the LAD artery was barely visible due to the severity of the blockage. After the angioplasty, the artery was widely patent, allowing blood to flow freely to the heart muscle.

severe blockage before and after stenting

This case illustrates the importance of choosing the appropriate test for each patient and the potential consequences of relying on a calcium score in symptomatic patients or those with high-risk profiles. In this case, the patient was at significant risk of complete occlusion and a massive heart attack, yet the initial test provided false reassurance. Only after further appropriate evaluation and intervention his life-threatening blockage was identified and treated.

Conclusion: Choosing the Right Test for the Right Patient

In conclusion, it’s essential to understand that coronary calcium scoring is a risk assessment tool and not a diagnostic test. It should only be ordered for asymptomatic and low-intermediate risk patients and should never be used to assess patients with cardiac symptoms, such as chest pain. It’s crucial to choose the right test for the right patient to ensure accurate diagnosis and proper treatment.

Coronary Calcium Scoring: Hidden Dangers for High-Risk and Symptomatic Patients (Video)

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