There are limitations to having a calcium score of “0”. If you don’t know what I’m talking about, let me explain 2 very important screening tools for heart disease. A coronary artery calcium score (CAC) is a CT scan of the heart that is non-invasive and measures calcified plaque in the arteries. Whereas, a Coronary CT angiogram (CCTA) provides detailed images of the arteries to detect blockages, both calcified and soft plaque. The coronary artery calcium score just detects stable or calcified plaque. So if your score is “0”, it means no calcium deposits are visible in the arteries. Since it only detects hard, stable calcified plaque, it can give us a false sense of reassurance. It tells us nothing about whether you have any soft, unstable, more dangerous plaque. There are limitations of a “0” calcium score.
Two new studies raise questions about the CAC’s predictive value in symptomatic patients. In one study, researchers investigated the plaque characteristics on CT angiograms from 108 symptomatic patients who subsequently developed acute coronary syndrome (ACS) during an average 3.4 years of follow-up. There was a matched group of 108 symptomatic patients who did not exhibit any acute coronary syndrome events. ACS is a group of diseases in which blood flow to the heart is diminished, such as a heart attack, ST-elevation and unstable angina. Almost 1/4 of each group had CAC scores of “0”. On CTA among these patients, non-calcified plaque (unstable) volumes were significantly greater on those who developed ACS than in those who did not.
About 70% of heart attack victims are considered low risk by traditional methods of assessing heart disease.
Here are some fun facts:
1. In the U.S., someone has a heart attack every 20 seconds.
2. At last 250,000 people die of heart attacks each year before they reach the hospital.
3. Stroke is the largest cause of death, ranking behind heart disease and cancer.
4. About 50% of heart attacks occur in patients with normal cardiovascular check-ups. They have no symptoms.
5. About 70% of heart attack victims are considered low risk by traditional methods of assessing heart disease.
In another study, 24,000 individuals with symptoms of coronary heart disease had CAC scores of “0” . When doing a CTA on these people, the prevalence of non-calcified plaque was 11%. Higher LDL cholesterol was also associated with significantly higher risks for non-calcified plaque and coronary heart disease events. These were strongest in those age 45 or younger.
The bottom line is that the CAC is not a good prognostic tool, even with a score of zero. About 1/4 of those who developed ACS had CAC scores of zero and a higher LDL cholesterol was a better predictor of downstream risk in those with scores of zero, especially in the younger population. We really need to look at all risk factors even in the absence of calcium to determine overall risk and use a CTA, especially in symptomatic patients.
An important tool I use to assess whether someone should have a CTA is an Lp-Pla2 and Lp(a) test. If elevated, the Lp-Pla2 means there is “hot” plaque and it needs to be assessed. This is high risk plaque! The other important blood test is an Lp(a) which is an inherited independent risk factor for heart disease and can increase the risk for blood clots.
The second tool I use is a CIMT (carotid intima media thickness) test. Since heart disease starts in the endothelial lining of vessels, it makes sense to look there. The CIMT test uses ultrasound (US) imaging to measure the thickness of the inner lining of the carotid artery, where vulnerable “hot” plaque can grow. This is the most sensitive screening test for stroke since 70% of stroke victims have plaque in the carotid artery and this is the major blood supply to the brain. This test is different than just getting a carotid US. The CIMT gives much more information. Talk to your practitioner about these tests that could save your life.
References: Parker, R. Consulting Radiologists, Ltd. Difference between Coronary Calcium Scoring and Coronary CT Angiogram. Blog 2/27/2025.
Jonas RA et al. CTA-derived plaque characteristics and risk of acute coronary syndrome in patients with coronary artery calcium score of zero: Insights from the ICONIC trial. AJR AM J Roentgenol. 2025 Jul; 225:e2431476.
Journal of the American College of Cardiology, May 2003.