CIMT is Used a Tool for Atherosclerosis-Related Event Prediction and for the Evaluating Atherosclerosis

Progression/Regression

400 scientific articles published in peer-reviewed journals during 2003 that included CIMT

Prediction of CVD events

Association with prevalent disease

Efficacy of pharmaceutical interventions

impact of diet and exercise modification

Association with traditional and non-

traditional risk factors

Evidence of genetic determinants of

atherosclerosis

Hypothesis Evaluated in these Papers

Advantages of Carotid IMT (cIMT) Testing

• Noninvasive, safe, inexpensive, accepted by patients, ethically sound

• Identifies minor (early) and major (late) ASO

• Nomograms (age, sex, and race-based) for normal values exist

• Predicts risk of future MI and STROKE

• Incremental predictive power

• Recommended by AHA for patients > 45 for “further clarification of CHD risk”

In one population-based study cIMT was the single risk factor best able to predict cardiovascular events, with a level of event

prediction nearly as great as all of the other risk factors combined !!! del Sol AL, et al. Stroke 2001, 32:1532

cIMT shown in clinical trials to

• Identify prevalence of cardiovascular disease (total CVD, angina, MI, Stroke, TIA, and PAD)

• Predict future risk of coronary heart disease and stroke (i.e., predicts incidence!)

• In these (and other prospective studies), CIMT remains a statistically significant predictor even after adjustment for know cardiovascular risk factors

ARIC Study, Burke GL, et al. Stroke 1995;26:286 Chambless EL, et al. Am J Epidemiol 2000;151:487

ARIC, Chambless LE, et al. Am J Epidemiol 1997;146:1483

The FDA-Accepted Means to evaluate Progression of ASO

• Quantitative angiograms

• cIMT

How Can CIMT be Used in Clinical Trials

As means of predicting the rate of progression/regression of atherosclerosis

in response to using/withholding an intervention

ProgressionRegression CIMT

Principles of Image Acquisition

3 segments can be evaluated:

- CCA- Bulb- ICA

Properly insonate the arteryMay need to use several angles

Focus on the WALL

- not the lumen -

Gated measurement (3 ECG

leads in place throughout

the study)

Technical Considerations

• High frequency transducer

• VCR or Digital storage

• High frame rate

• High dynamic range

• One focal zone at the level of interest

• ECG on

• TGC slope numbers if possible displayed

Segment: R CCA

Angle of insonation: 135

Image Acquisition

• Doppler of the CCA, ECA, and ICA

• Transverse scan to look at intima– 135 degree

approach for the right

– 225 degree approach for the left

• AP diameter of the distal CCA

• Find the Y bifurcation Best practice for identifying the flow divider

Identify CCA

Identify ECA

Identify ICA

BulbICACCA

Flow Divider