The document discusses that less obstructive plaques pose a greater risk of coronary occlusion than severely obstructed plaques due to their greater numbers. It also states that the aggregate risk of rupture from many non-significant lesions exceeds that of fewer significant lesions, so a myocardial infarction is more likely to originate from a non-significant lesion. Additionally, while electron beam tomography (EBT) cannot identify vulnerable plaques directly, it can identify vulnerable patients based on their coronary artery calcium (CAC) scores and percentiles, as risk increases with higher scores. EBT is also useful for estimating prognosis and tracking changes in plaque burden in response to treatment over time.

1. Plaque Severity and Coronary Occlusion:Plaque Severity and Coronary Occlusion:
Or, Why Plaque Severity is More Important Than StenosisOr, Why Plaque Severity is More Important Than Stenosis
“…“…the less obstructive plaques gave risk to more occlusionsthe less obstructive plaques gave risk to more occlusions
than did the severely obstructed plaques because ofthan did the severely obstructed plaques because of
their much greater numbertheir much greater number....”....”
Falk, Shah, Fuster: Coronary Plaque DisruptionFalk, Shah, Fuster: Coronary Plaque Disruption
Circulation 1995;92:pg. 658Circulation 1995;92:pg. 658
““Because the aggregate risk of rupture associated with manyBecause the aggregate risk of rupture associated with many
nonsignificant lesions exceeds that of the fewer significantnonsignificant lesions exceeds that of the fewer significant
lesions, a myocardial infarction will more likely originatelesions, a myocardial infarction will more likely originate
from a nonsignificant lesion.”from a nonsignificant lesion.”
Kern, Meier: Evaluation of the Culprit PlaqueKern, Meier: Evaluation of the Culprit Plaque
Circulation 2001;103;3142Circulation 2001;103;3142

2. EBT and Coronary Artery CalciumEBT and Coronary Artery Calcium
No calcification – EBT/CACNo calcification – EBT/CAC
55 year old woman with chest pain55 year old woman with chest pain
? “low density” plaque?? “low density” plaque?
““low density” plaquelow density” plaque
With stenosisWith stenosis
EBAEBA

3. CAC by EBT and Atherosclerotic PlaqueCAC by EBT and Atherosclerotic Plaque
Although not all plaque is visualized by EBCTAlthough not all plaque is visualized by EBCT
and “soft” plaque is currently not measured,and “soft” plaque is currently not measured,
the greater the calcium score,the greater the calcium score,
the greater the plaque burdenthe greater the plaque burden

4. CAC by EBT:CAC by EBT:
““vulnerable” plaque vs “vulnerable” patientvulnerable” plaque vs “vulnerable” patient
““Risk” increases as an individuals CACRisk” increases as an individuals CAC
score and/or percentile rank increasesscore and/or percentile rank increases
Thus, although EBCT and CAC is not ableThus, although EBCT and CAC is not able
to identify the “vulnerable” plaque, it CANto identify the “vulnerable” plaque, it CAN
identifyidentify “the“the vulnerable patient”vulnerable patient”

5. EBT and Coronary Artery CalciumEBT and Coronary Artery Calcium
 Estimate Prognosis? YESEstimate Prognosis? YES
but does so based upon estimates ofbut does so based upon estimates of
total coronary atherosclerotic plaque burdentotal coronary atherosclerotic plaque burden
and not on visualization of “hard” vs “soft” plaqueand not on visualization of “hard” vs “soft” plaque

6. EBT and CAC:EBT and CAC:
coronary remodeling and CACcoronary remodeling and CAC
CAC
LM/LAD RCA
43 y/o woman
+FHx
5.5 mm
8 mm
Is this patient
at higher risk
due to coronary
artery remodeling?

7. Annualized Rates of Progression - EBTAnnualized Rates of Progression - EBT
30.2%/year
12%/year
0 10 20 30 40 50 60
Untreated
Treated
n = 792
n = 292
Range 5%-20%
Range 22%-52%
Composite of 9 studies – weighted averageComposite of 9 studies – weighted average

8. EBT is the only non-invasive method visualizingEBT is the only non-invasive method visualizing
the coronary arteries that has been shown tothe coronary arteries that has been shown to
• Track changes in coronary “plaque” in responseTrack changes in coronary “plaque” in response
to lipid lowering medications, andto lipid lowering medications, and
• AndAnd suggest that the magnitude of serial changes cansuggest that the magnitude of serial changes can
potentially be of value to predict the development ofpotentially be of value to predict the development of
acute coronary syndromesacute coronary syndromes
The Search for the Vulnerable Patient

9. MRI
1. Plaque composition
2. ?Contrast?
Inflammatory Markers
1. hs-CRP
2. fibinogen
3. ?
??????
? historical
? other imaging
? lipoproteins
The Search for the Vulnerable Patient
Pieces of the Puzzle
EBCT
1. Calcium [percentile]
2. Calcium – serial changes
3. Remodeling
4. Contrast (soft plaque?)

10. MRI
1. Plaque composition
2. ?Contrast?
Inflammatory Markers
1. hs-CRP
2. fibinogen
3. ?
??????
? historical
? other imaging
? lipoproteins
The Search for the Vulnerable Patient
Pieces of the Puzzle
EBCT
1. Calcium [percentile]
2. Calcium – serial changes
3. Remodeling
4. Contrast (soft plaque?)