4. Measurement of CIMT
• Distal common carotid artery
• Carotid bulb
• Proximal internal carotid artery
Different sites of measure
CIMT: carotid intima-media thickness
5. Standardization of CIMT measurement
• Longitudinal scan of CCA
• Far wall of CCA
• At least 5 mm from carotid bulb
• 10 mm segment of far wall
CCA: common carotid artery – CIMT: carotid intima-media thickness
Touboul PJ et al. Cerebrovasc Dis 2012;34:290–296.
6. CCA, bifurcation & origin of ICA & ECA
CCA: common carotid artery – ECA: external carotid artery – ICA: internal carotid artery
Touboul PJ et al. Cerebrovasc Dis 2012;34:290–296.
Double arrow line corresponds to end of CCA
where near & far walls start diverging
8. Automated measurement of CIMT
Radiofrequency signals
QI 0.94 – Maximal 0.713 mm – Mean 0.648 mm – SD 0.047 mm
Quality Index: 94% of 150 measures could be performed
Maximal: highest value obtained from all the measures
Mean: average of all measurements that could be performed
CIMT: carotid intima-media thickness
Touboul PJ et al. Cerebrovasc Dis 2012;34:290–296
14. CIMT & plaque
1. Focal encoarching into arterial lumen of at least 0.5 mm
2. > 1.5 mm intima-media thickness
Mannheim IMT consensus. Cerbrovasc Dis 2012;34:290 –296.
Plaques
15. Indications of CIMT measurement
• Screening for subclinical atherosclerosis
• Risk stratification for future CVD-related events
• Assessment of cardio-vascular drug efficacy
16. CIMT as predictor of future CV events
One-time CIMT measurement
14 studies & 45,828 asymptomatic individuals
Median follow-up 10.8 years
Hazard ratio per 0.10 mm mean common CIMT difference:
- First myocardial infarction 1.08 (95% CI: 1.05 – 1.10)
- First stroke 1.12 (95% CI: 1.10 – 1.15)
Individual participant data meta-analysis
CI: confidence interval
Den Ruijter HM et al. JAMA 2012; 308:796.
17. • 16 studies, 36,984 patients without known CV disease
• Mean follow-up 7 years with yearly progression rates of
CIMT (mean & maximum CIMT of CCA, bifurcation & ICC)
• Baseline CIMT was independent predictors of future CVE
• Progression of CIMT was not associated with future events
CIMT as predictor of future CV events
Serial CIMT measurement
Individual participant data meta-analysis
CCA: common carotid artery – CVE: cardio-vascular events – ICC: internal carotid artery
Lorenz MW et al. Lancet 2012; 379:2053.
18. Technical issues in CIMT measurement
Touboul JP. Front Neurol Neurosci 2015;36:31-39.
Patient
Age
Sex
Race
Tissue echogenicity
Neck anatomy
Risk factors
Device
Frequency
Gray-scale
Depth settings
Gain settings
Frame rate
Sonographer
Education
Far wall
CCA/Bif/ICA
Left/right
Plaque/no plaque
Measurement
Manual
Semi-automatic
Software
Mean/max
Cardiac cycle
19. • Low risk individuals <10%
• Intermediate risk individuals 11-20%
• High risk individuals >20%
Framingham coronary heart disease risk score
Most commonly used score
10-year risk of coronary heart disease events
21. FRS: Framingham risk score
http://www.cscc.unc.edu/aricnews/CIMTCHD/RiskCalc2.html
ARIC study
CIMT & carotid plaque included in FRS
13,145 participants without CVD
7% improvement in all subjects
17% improvement in intermediate risk subjects
22. Assessment of cardio-vascular drug efficacy
• CIMT used to test efficacy of CV drugs in clinical trials
• Lipid-lowering: statins, niacin, ezetimibe
Anti-hypertensive, anti-obesity, antioxidants
• Modification of therapy based on CIMT not shown to
alter end points (death, myocardial infarction, stroke)
CIMT is not used in clinical practice to monitor effects
of medical therapy in individual patient
23. CIMT measurement in primary prevention
Guidelines differ in their recommendations
1 Naghavi M et al. Am J Cardiol 2006;98:2H–15H.
2 Greenland P et al. Circulation 2010;122:2748–2764.
3 Society of Atherosclerosis Imaging and Prevention. Atherosclerosis 2011;214:43–46.
4 Goff DC Jr et al. J Am Coll Cardiol 2014; 63:2935.
Year Guidelines Recommendations
2006 Screening for Heart Attack Prevention
and Education (SHAPE)1
All individuals
2010 American College of Cardiology (ACC)2 Individuals at intermediate risk
2011 Society of Atherosclerosis Imaging and
Prevention (SAIP)3
Intermediate-risk patients
Patient with metabolic syndrome
Older patients
2014 American College of Cardiology (ACC)4 No routine use in clinical practice
24. Toward better evaluation of atherosclerosis
Guidelines of ACC/AHA 2014
• Family history
• High sensibility CRP (hs-CRP)
• Coronary artery calcium score (CACS)
• Ankle-brachial index (ABI)
ACC/AHA: American college of cardiology/American heart association
4 Goff DC Jr et al. J Am Coll Cardiol 2014; 63:2935.
Newer risk markers for quantitative risk assessment
26. Grading arterial disease using ankle brachial index
ABPI Comment
> 1.3 Falsely high value (suspicion of medial sclerosis)
0.9 – 1.3 Normal finding
0.75 – 0.9 Mild peripheral arterial disease
0.4 – 0.75 Moderate peripheral arterial disease
< 0.4 Severe peripheral arterial disease
ABPI: Ankle Brachial Pressure Index
Stiegler H & Brandl R. Ultraschall in Med 2009;30:334–363.
27. Carotid hemodynamics parameters
PSV: pic systolic velocity – EDV: end diastolic velocity – RI: resistivity index
Kim GH et al. Korean Circ J 2017;47(1):1-8.
Decreased PSV
Decreased EDV
Increased RI
More predictive of CV events than CIMT
in several preliminary studies
28. Conclusion
• CIMT is indicator of subclinical atherosclerosis
• CIMT can predict the risk of future CV events
• Other single or combined parameters could be more
predictive of future CV events than CIMT
Typically, normal common carotid CIMT at age 10 is approximately 0.4 to 0.5 mm, while from the fifth decade of life onward this progresses to 0.7 to 0.8 mm or more [3].
Measurement in diastole:
systolic expansion of lumen causes the CIMT to become thinner.
Measurement
Until additional data are available that directly correlate CIMT measurement with improvements in hard outcomes (ie, death, myocardial infarction, stroke), we do not recommend routine CIMT measurement.
While the highest ankle pressure is used in most studies, the sensitivity for the detection of a relevant arterial occlusion disease of 68% was able to be increased to 93% with a comparable specificity of almost 100% in a current study for an ABI < 0.9 by using the lowest foot artery pressure value.