Carotid intima-media thickness (CIMT) measurement is a simple 15 minute screening test, using ultrasound, that provides insight into a person’s cardiovascular health. It detects the earliest traces of plaque within the layers of the artery wall, years before there is enough blockage of blood flow to cause heart attack or stroke. It is also used to determine “arterial age”, which compares a person’s average carotid artery thickness to a person of that age who is at normal risk.
CIMT is the ideal screening test as it is non-invasive, inexpensive and capable of detecting disease very early so that steps may be taken to reverse or slow the disease process. CIMT is shown in numerous studies to help predict who is at increased risk for heart attack or stroke. It can be used in men and women starting at any age to detect the earliest signs of artery plaque. It can differentiate between soft (active) plaque and hard (stable) plaque which help us gauge whether or not existing plaque is actively growing.
CIMT measures the distance between the intima (inner) and media (middle) layers of the artery wall. If there is inflammation and active cholesterol plaque present then the distance increases. If the thickness is above the 75th percentile for your age then significant activity is happening and your risk for cardiovascular disease is increased.
“Arterial age” (AA) gives an idea of the age of your arteries compared with normal arteries at your age. For example, at age 55 a slightly thickened CIMT might represent the artery of a 65 year old, thus an AA of 65. If the arterial age is more than 5 yrs greater than actual age then there is significant increased risk of a cardiovascular event.
CIMT is measured in the carotid artery just below the point in the neck where it splits into the internal and external branches. In this way it is standardized to be measured at the same point each and every time, thus is highly reproducible. It is resulted in millimeters (mm) and a thickness >1mm is considered increased.
There are 4 main categories of results to classify results of CIMT and plaque:
- Normal CIMT and no plaque. This is truly normal and the risk of cardiovascular disease is very low.
- Abnormal CIMT and no plaque. Here you have early disease with signs of inflammation in the artery wall but no plaque formation, yet. The good news is this is very early in the disease process where it is easier to address.
- Normal CIMT and presence of plaque. This situation suggests that there was active plaque formation in the past, but now the inflammation in the artery wall has settled down. It would be more likely the plaque is hard, stable plaque. This is where it is important to determine if the plaque is soft, mixed (heterogenous) or hard plaque. Again, soft plaque is very unstable and dangerous, mixed plaque less so, and hard plaque more stable.
- Abnormal CIMT and presence of plaque. This is the most dangerous category and has the highest risk. Like category 2 this situation is serious because the inflammation that causes plaque is present, yet much more concerning because the process is much further along.
Category 1 results should guide one to continue current health practices and repeat screen every 2-10 years depending upon your age and how aggressive you are with preventive screening.
Category 2-4 results generally indicate a visit with your healthcare provider is indicated to sort out what needs to be done to improve the situation. This always means addressing any lifestyle factors that are known to encourage the plaque formation, such as diet, exercise, weight control, smoking, and stress. We also recommend advanced blood tests that help define the plaque process more in depth than a simple cholesterol panel and better guide to specific therapies. Repeat screening in 6-12 months is recommended.
Here is a great example of why we do these scans. The initial scan 1 showed significant artery thickening and plaque. A year later scan 2 shows marking improvement caused by our patient eating a more plant based diet combined with a few supplements, and scan 3 shows CIMT back to normal for his age. Also note by scan 3 the plaque is more calcified, or hard, which means it’s stable. Getting the scan probably saved him from impending heart attack or stroke.
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If you are interested in getting an ultrasound for CIMT screening call our office for scheduling. We have specialists from Denver visit monthly to do the scans. The cost is $200. For more information on their credentials visit vasolabs.com.