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 occlusionsthan did the severely obstructed plaques because of than did the severely obstructed plaques because of their much greater numbertheir much greater number....”....”Falk, Shah, Fuster: Coronary Plaque DisruptionFalk, Shah, Fuster: Coronary Plaque DisruptionCirculation 1995;92:pg. 658Circulation 1995;92:pg. 658

““Because the aggregate risk of rupture associated with manyBecause the aggregate risk of rupture associated with manynonsignificant lesions exceeds that of the fewer significantnonsignificant lesions exceeds that of the fewer significantlesions, a myocardial infarction will more likely originate lesions, 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 PlaqueCirculation 2001;103;3142Circulation 2001;103;3142

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” plaqueWith stenosisWith stenosis

EBAEBA

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

CAC by EBT:CAC by EBT:““vulnerable” plaque vs “vulnerable” patientvulnerable” plaque vs “vulnerable” patient

““Risk” increases as an individuals CAC Risk” 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 ableto identify the “vulnerable” plaque, it CANto identify the “vulnerable” plaque, it CAN

identify identify “the “the vulnerable patient”vulnerable patient”

EBT and Coronary Artery CalciumEBT and Coronary Artery Calcium

Estimate Prognosis? YESEstimate Prognosis? YES

but does so based upon estimates of but 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

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 mmIs this patientat higher riskdue to coronaryartery remodeling?

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

EBT is the only non-invasive method visualizingEBT is the only non-invasive method visualizingthe coronary arteries that has been shown to the 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 can suggest that the magnitude of serial changes can

potentially be of value to predict the development of potentially be of value to predict the development of acute coronary syndromesacute coronary syndromes

The Search for the Vulnerable Patient

MRI1. Plaque composition2. ?Contrast?

Inflammatory Markers1. hs-CRP2. fibinogen3. ?

??????? historical? other imaging? lipoproteins

The Search for the Vulnerable Patient

Pieces of the Puzzle

EBCT1. Calcium [percentile]2. Calcium – serial changes3. Remodeling4. Contrast (soft plaque?)