CIMT stands for carotid intima-media thickening. The intima and media are the two innermost layers of the arterial walls, or blood vessels. There’s a third layer, the outer layer, called the adventitia. The intima is the innermost layer and the media is the middle layer. The media is largely made up of smooth muscle. Thickening of the intima-media indicates arteriosclerosis increasing one’s risk of a heart attack or stroke. CIMT can be easily measured by ultrasound.
CIMT is a more accurate predictor of cardiovascular disease than any other risk factor alone – that’s saying something.
Measuring CIMT is important because the traditional risk factors for heart disease (smoking history, family history, history of diabetes, hypertension and high LDL cholesterol, and low HDL cholesterol) fail to identify many who suffer heart attacks and strokes. Naghavi reports in the book Asymptomatic atherosclerosis that 77% of those hospitalized with coronary artery disease had normal LDL levels.
So measuring CIMT is another tool to better determine your risk of cardiovascular disease, and should you have it, how aggressive to manage it.
Ultrasound is a non-invasive imaging study and has many applications. Plus, ultrasound does not involve radiation. CIMT can be measured accurately by carotid ultrasound, a test that can be performed in a matter of minutes. Ultrasound can also detect hard and soft plaque in the arteries. It is the rupture of plaque that triggers an inflammatory response ultimately leading to heart attacks and strokes. CT scanning is another way to detect calcification of arteries. But CT scanning detects only hard or calcified plaque, but not soft plaque that ultrasound can detects. Plus, CT imaging also involves radiation.
What if I have Thick IMT or Plaque?
First, the good news is atherosclerosis is reversible. If you have plaque and/or thickening of the intima-media you need to be aggressively treated. This involves medications to manage blood pressure and to lower your LDL cholesterol and raise your HDL cholesterol (if it’s low). Treatment also involves weight loss, regular exercise, stress management, dietary changes, and if you’re a smoker – smoking cessation.
In essence, intima-media thickening and/or plaque are additional risk factors, but risk factors with stronger predictive power for those at risk heart attacks and strokes than the traditional risk factors.
Who Should Get a Carotid Ultrasound?
The following groups should consider a carotid ultrasound study.
- Men over age 40
- Women over age 50 (sooner if menopausal)
- Men with erectile dysfunction
- Anyone with a family history of premature coronary heart disease
- Anyone with a history of smoking
- Anyone with rheumatoid arthritis, psoriasis, or other autoimmune diseases
- Anyone with metabolic syndrome (high blood pressure, low HDL, elevated triglycerides, overweight, insulin resistance)
- Anyone overweight
- Anyone with 2 or more risk factors for coronary heart disease
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