Carotid Intima-Media Thickness Test

Although countries are focusing on fighting cardiovascular disease (CVD), the burden of coronary artery disease continues to rise globally. Atherosclerosis, the precursor of CV events, keeps progressing insidiously without symptoms. Let’s take a look at the reasons why this is happening, as well as at the solutions for the problem. Among other things, we will introduce some proposals from the expert group of Heart Attack Prevention and Education (SHAPE). We will also explain how the non-invasive CIMT measurement is discussed in some expert communities as part of broader cardiovascular education.

This article was last reviewed by Svetlana Baloban, Healsens, on January 24, 2020. This article was last modified on 7 February 2020.

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To understand what is measured with this test, let’s look at the structure of the coronary artery wall. It consists of three layers. The inner layer is called intima, the middle layer is called media, and the outer one is known as the adventitia. The layers of intima and media lie the deepest. So an increase in their thickness can be a sign of plaque formation. It is the thickness of the intima-media complex of the carotid neck arteries which feed the brain that is usually measured.

The relation between carotid intima-media thickness and diseases

Interestingly, some studies¹ have shown that cIMT is strongly and linearly related to age. Up to 25 years, the thickness is not higher than 0.6 mm. But by the age of 45 years, the CMM is on average higher than 0.8 mm. Some other studies² have also indicated that researchers have noted correlations between artery wall measurements, age, and general heart health markers.

Meanwhile, the ESH/ESC hypertension guidelines (2013) note that some artery wall thickness thresholds are discussed as indicators to explore overall cardiovascular wellness with a clinician³.

Professional groups have published research opinions on how artery measurements might relate to heart-health risk discussions. Values from the 25th to the 75th percentile are an average cardiovascular risk. And values ≤ 25th percentile are considered low risk.

In other words, the larger CIMT the greater the risk of cardiovascular disease. The process is also associated with aging. However, you should not think that since aging is inevitable, then there is no point in measuring CIMT, since the good news is that recent studies suggest this process can be influenced⁷ and even reversed⁸ by increasing physical activities and treating it with medications.

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Who is recommended to take a carotid intima-media thickness test?

Despite the many benefits and a wealth of information, screening for IMT has not yet been added to the CVD prevention guidelines. In early 2007, Circulation magazine published a report⁹ with the conclusion that IMT of the carotid arteries is a serious factor in the development of stroke and heart attack. Nevertheless, a few months later, the American Preventive Task Force recommended asymptomatic people not to undergo an IMT test regularly.

A common strategy is to encourage people interested in their cardiovascular wellbeing to discuss various assessment options, including CIMT, with a care provider before deciding what makes sense for them. And vice versa, respectively. Moreover, the problem is that there is no uniform risk assessment system. Therefore, different organizations offer their own options. We’ve already reviewed different Cardiovascular Risk Assessment approaches but let’s take a look at some of them once more.

How to calculate cardiovascular risk?

As we mentioned above, there is currently no unified risk assessment system. At the same time, there are various risk calculators such as Framingham scores, Reynolds risk scores, ASCVD, SCORE, etc. European preventive guidelines note that professionals may consider the CIMT measurement when reviewing cardiovascular health with people who have some risk factors. Most asymptomatic middle-aged adults fall into this category. You can explore general heart-health risk questionnaires in the Healsens app for educational purposes.

At the same time, the NCEP recommends estimating the risk using the Framingham risk score. You can calculate it as well. On the other hand, the American Society of Echocardiography recommended adding the following extra criteria¹⁰:

• family history of premature CVD in a first-degree relative (men < 55 years old, women < 65 years old);
• people younger than 60 years old with severe abnormalities in a single risk factor. In the situation where they would not be candidates for pharmacotherapy;
• women younger than 60 years old with at least two CVD risk factors.

We wrote more about various risk calculators separately. But what is their importance? Why are we looking at these tools in such detail? The answer is simple. Health professionals may consider multiple factors when discussing lifestyle adjustments for heart health. Indeed, as we wrote above, atherosclerotic cardiovascular disease can be prevented. However, cardiovascular disease remains the leading cause of death and severe disability worldwide. What’s the matter?

What’s the problem with the traditional approach?

It turned out that traditional methods of preventing A-CVD have proven largely insufficient. Indeed, studies indicate that traditional risk calculations explain only 60-65% of CVD risk¹¹. In addition, it was shown that the calculated risks don’t always lead to disease development. Conversely, many acute clinical events occur in patients with moderate or no risk. The most probable reason for this is that many other factors are not included in the calculations.

The Screening for Heart Attack Prevention and Education (SHAPE) Task Force

To solve this problem, an international group of experts created screening recommendations for Heart Attack Prevention (SHAPE). They have already proposed the First SHAPE Guideline in primary prevention of A-CVD.

A suggested informational flow looks at non-invasive heart-health indicators that people can discuss with their care team.

Look at the first Screening for Heart Attack Prevention and Education (SHAPE) Guideline.

FURTHER READING

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1. Relation between age and carotid artery intima-medial thickness: a systematic review
2. Intima-media thickness: a new tool for diagnosis and treatment of cardiovascular risk
3. Intima-media thickness: appropriate evaluation and proper measurement
4. Beta-cell function is associated with carotid intima-media thickness independently of insulin resistance in healthy individuals
5. Gallstones are Associated with Intima-Media Thickness of Common Carotid Arteries in Men
6. Markers for the risk of progression from mild cognitive impairment to Alzheimer’s disease
7. Subtherapeutic, low-dose fluvastatin improves functional and morphological arterial wall properties in apparently healthy, middle-aged males–a pilot study
8. Reversing the Cardiac Effects of Sedentary Aging in Middle Age-A Randomized Controlled Trial: Implications For Heart Failure Prevention
9. Carotid Atherosclerosis Is a Stronger Predictor of Myocardial Infarction in Women Than in Men
10. Use of Carotid Ultrasound to Identify SubclinicalVascular Disease and Evaluate Cardiovascular Disease Risk
11. Assessment and Relevance of Carotid Intima-Media Thickness (C-IMT) in Primary and Secondary Cardiovascular Prevention