How is the CIMT different from a Treadmill Stress Test?

Stress tests have been used for decades in the assessment of coronary artery obstruction or blockage. These tests are useful to sort out symptoms, especially when attempting to determine whether chest pain or shortness of breath is related to coronary artery atherosclerosis. 

Stress tests, however, are not good at detecting early atherosclerosis that isn’t blocking blood flow.  Plaque that is new and unstable may not block flow but could rupture and cause a clot to suddenly and completely block flow and result in a heart attack. 

It is not rare for a person to pass a stress test and have a heart attack a short time later. 

Despite these facts, stress tests continue to be used to reassure patients that they are “OK.”  A negative stress test means you aren’t going to be helped by a stent or surgery to address blockage.  It does not truly reassure that no atherosclerotic plaque is present.  A false sense of reassurance can be bad.

Carotid Intima Media Thickness (CIMT) identifies the earliest stages of atherosclerosis.  This is important because when you know you have a disease and are given the tools to prevent its progression, you can avoid the complications of late stage disease, including death and disability without warning.  You can also avoid the costs and complications of expensive and invasive treatments.

To sort out symptoms that could be related to your coronary arteries, a stress test is helpful. But to determine if you should take measures to improve your arterial health to avoid heart attack or stroke and their complications and treatments, Carotid IMT is far more useful. 

CIMT is also less expensive, less time consuming and does not require effort to be evaluated. 

 

I had a coronary calcium score. Should I have a Carotid Intima Media Thickness too?

In other words, does a coronary calcium score and a Carotid Intima Media Thickness (CIMT) scan give the same information? 

Although they both detect atherosclerosis, they do so at different stages of disease.  Costs for both tests in our community are comparable, and the CIMT scan is far more portable.

In addition, I have 2 concerns with coronary calcium score.  First, it is not useful for measuring the effects of treatment.  Without going into great detail, it does not improve when artery health improves because calcium deposition occurs late in the development of plaque and will not decrease with treatment.  It represents old scar. 

The second concern is that early, new, soft, non-calcified, dangerous unstable plaque is not detected because it has not yet become calcified.  A test that misses the most dangerous form of the disease is not as useful as one would hope.

The Carotid Intima Media Thickness Scan detects plaque at all stages, including the more dangerous non-calcified plaque mentioned above.

Granted, it is a surrogate sample measurement used to measure atherosclerosis generally.  It does not look directly at the arteries supplying the heart. 

But if you have plaque in your carotid arteries, you should assume you have plaque elsewhere, including the coronaries.  Treatment that improves the carotid artery health improves arterial health generally. 

And improvement (or progression) can be measured and documented.  The effects of treatment to reduce atherosclerotic burden can be seen.  If improvement isn’t seen as expected, treatment can be adjusted. 

Coronary calcium score is not useful for serial measurement of atherosclerosis development.

At the Center for Prevention of Heart Attack & Stroke, we do CIMT first.  If no disease is detected in an individual where it is expected due to a high risk profile, coronary calcium score is a consideration to be more sure the coronaries are not diseased before the carotids.  

I hope you found this answer helpful!