Electron Beam Computed Tomography in the Age of 64 Slice CT

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Electron Beam Computed Tomography in the Age of
64 Slice CT

• Matthew J. Budoff, MD, FACC
• Associate Professor of Medicine
• Division of Cardiology
• Harbor-UCLA Medical Center, Torrance CA

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5 USES OF Coronary Artery Calcium

• Use a calcium score to screen patients with
  moderate (intermediate) Framingham risk
• Positive CAC scans indicate incremental risk
• Alters therapeutic goal (LDL, BP, etc)
• Identify patients who do not need further cardiac
  evaluation (scores of zero)
• Consider serial imaging as ongoing management
  tool (progression)
• Improve compliance
• Non-invasive Angiography

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All Cause Mortality in Patients Without Known CAD
All Cause Mortality NDR n 10,377 asymptomatic
men and women f/u 5.03.5 yrs.
EBT found to be independent and incremental to
risk factors
Relative Risk
DM
Smoke
HTN
lt10
101-400
gt1000
10-100
401-1000
Shaw, Raggi et al Radiology 2003
EBT Coronary Calcium Score
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Prediction of Cardiac Events in
Asymptomatic Patients by EBT The St. Francis
Heart Study, JACC 2005
Annual Event Rate ()
SFHS 3
Baseline EBT Calcium Score
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Outcome Data St Francis Randomized Trial

• This study was a double-blind, placebo-controlled
  randomized clinical trial of atorvastatin 20 mg
  daily, vitamin C 1 g daily, and vitamin E
  (alpha-tocopherol) 1,000 U daily, versus matching
  placebos in 1,005 asymptomatic, apparently
  healthy men and women age 50 to 70 years with
  coronary calcium scores at or above the 80th
  percentile for age and gender. All study
  participants also received aspirin 81 mg daily.
  Mean duration of treatment was 4.3 years.
• Treatment reduced low-density lipoprotein
  cholesterol by 39.1 to 43.4 (p lt 0.0001), while
  reducing clinical endpoints by 30 (6.9 vs.
  9.9).
• Event rates were related to baseline calcium
  score (pre-specified analysis) and have been
  reduced in a subgroup of participants with
  baseline calcium score gt400 (8.7 vs. 15.0,
  p0.046 42 reduction).
• The 30 reduction in the primary end point of
  this study is similar to the reduction of ASCVD
  events seen in other large randomized clinical
  trials of statins, a class of drugs with
  unquestionable efficacy in this application

Arad Y et al. Treatment of Asymptomatic Adults
with Elevated Coronary Calcium Scores with
Atorvastatin, Vitamin C, and Vitamin E The St.
Francis Heart Study Randomized Clinical Trial. J
Am Coll Cardiol 2005 46 166-172.
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Near- and Long-Term Survival from 2 Cohorts
over 35,000 patients
n10,377 n25,257
1.00
1.00
99.4
99.4
97.8
97.8
0.95
95.2
0.95
94.5
90.4
0.90
0.90
93.0
0.85
0.85
81.8
0.80
0.80
76.9
0.75
0.75
0.00
2.00
4.00
6.00
8.00
10.00
12.00
0.00
1.00
2.00
3.00
4.00
5.00
Time to Follow-up (Years)
Time to Follow-up (Years)
CAC Score (5 Yr
Mortality 1.2) (12-Yr Mortality
2.1) Difference 0-10
99.4 99.4
0.0 11-100 97.8
97.8 0.0 101-400
95.2 94.5
0.7 401-1,000 90.4
93.0 0.6 gt1,000
81.8 76.9
4.9
?21503, plt0.0001, interaction plto.0001
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Cooper Clinic Study - 10,782 Patients 3.5 year
follow-up
Nonfatal MI CHD Death
21.1 (7.8-57)
9.7 (3.6-26)
6.0 (2.1-17)
2.7 (0.8-9.3)
Ref
Adjusted age, history of diabetes, hypertension,
elevated cholesterol, over weight
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Taylor et al PACC Study JACC 2005

• 2000 patients, mean age 43
• Coronary calcium was associated with an 11.8-fold
  increased risk for incident coronary heart
  disease (CHD) (p 0.002) in a Cox model
  controlling for the Framingham risk score.
• In young, asymptomatic men, the presence of
  coronary artery calcification provides
  substantial,
• cost-effective, independent prognostic value in
  predicting incident CHD that is incremental to
  measured coronary risk factors.

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Anand EHJ 2006 510 Diabetics
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MESA OUTCOMES
CAC Score Number of hard1 events/Number at risk Hazard Ratio 95 C.I p-value Number of CHD events/Number at risk Hazard Ratio 95 C.I p-value
0 8/3411 1.0 15/3411 1.0
1-100 25/1728 5.27 (2.37,11.73) lt0.00005 39/1728 4.47 (2.45,8.13) lt0.00001
101-300 24/752 10.78 (4.79,24.27) lt0.00001 41/752 10.26 (5.62,18.71) lt0.00001
300 or greater 32/833 11.97 (5.40,26.51) lt0.00001 67/833 14.13 (7.91,25.22) lt0.00001
1 Includes only myocardial infarction and CHD
death
Detrano Et al. J Am Coll Cardiol 200749101A.
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MESA Study 6,814 Patients 3.5 year follow-up
Nonfatal MI CHD Death
21.1 (7.8-57)
9.7 (3.6-26)
6.0 (2.1-17)
2.7 (0.8-9.3)
Ref
Fully adjusted Detrano et al ACC Abstract -
JACC March 07
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Calcium Versus Framingham
n 44
n 29
n 27
Myocardial Infarction ()
n 18
n 17
n 5
n 5
n 4
n 1
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NCEP ATP-III Noninvasive Testing - 2001
measurement of coronary calcium is an option for
advanced risk assessment. High coronary calcium
scores (e.g., gt75th percentile for age and sex)
denotes advanced atherosclerosis and provides
rationale for intensified LDL-lowering therapy.
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European Guidelines

• European Guidelines on Cardiovascular Disease
  Prevention in Clinical Practice (2003) which
  state that Coronary calcium scanning is thus
  especially suited for patients at medium risk,
  and use CAC to qualify conventional risk
  analysis.

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AHA Circulation 2005
This recommendation to measure atherosclerosis
burden, in clinically selected intermediateCAD
risk patients (eg, those with a 10 to 20
Framingham 10-year risk estimate) to refine
clinical risk prediction and to select patients
for altered targets for lipid-lowering therapies.
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MEDICARE LCD- California

• 10. Quantitative evaluation of coronary calcium
  to be used as a triage tool in patients with
  chest pain of suspected cardiac etiology or clear
  evidence of myocardial ischemia and unknown
  Agatston score to determine the appropriateness
  of coronary CTA vs. catheter coronary
  angiography.
• 11. Quantitative evaluation of coronary calcium
  to be used as a triage tool for lipid-lowering
  therapy in patients with an intermediate to high
  Framingham risk score. Per recommendations of the
  American College of Cardiology, California
  chapter, and California Radiological Society, two
  of the following diagnoses should be present
  diabetes, metabolic syndrome, hypertension,
  family history of cardiac or vascular disease,
  lipid abnormalities, smoking, or obesity. Since
  patients are generally over age 65, this is a
  total of 3 Framingham risk factors.
• 12. Quantitative evaluation of coronary calcium
  in patients with an equivocal stress imaging test
  or in cases in which discordance exists between
  stress imaging testing and clinical findings.

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Blue Shield February 2005
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Blue Shield February 2005
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New Guidelines From AHA
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AHA 2006

• virtually all of the prognostic and
  epidemiological data derived for CACP have been
  performed with EBCT
• On the basis of the substantial validation data,
  EBCT remains the reference standard for CACP
  measurement
• The AHA Writing Group proposes that the following
• minimum requirements be met in scanning for CAC
• 1. Use of an electron beam scanner or a 4-level
  (or greater) MDCT scanner

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AHA CT Angiography

• Where MDCT is used for CT angiography, the AHA
  Writing Group currently recommends a minimum of
  16-slice capability, submillimeter collimation,
  and 0.42-second gantry rotation with
  retrospective ECG gating. If EBCT is used, 1.5-mm
  slice thickness should be used.

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Radiology 2005 235723727
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Cardiac CT EquipmentRecommendations

• The availability of a multidetector row helical
  CT or an electron-beam CT scanner is a
  requirement for cardiac CT applications,
  especially for coronary artery calcium scoring
  and CT angiography.
• For multidetector row CT, at least four detector
  rows are preferred for calcium scoring and at
  least 16 are preferred for CT coronary
  angiography.

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Presenter Disclosure Information
Disclosure Information...The following
relationships exist related to this presentation
Budoff MJ speakers Bureau, GE
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Limitations of Coronary Angiography

• 15-35 of all angiograms done have no significant
  luminal narrowing
• Luminogram no wall (plaque) information
• Average costs high, reimbursement to physician -
  limited

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Coronary artery imaging - small
diameters (1-4 mm) - complex
anatomy - rapid motion
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Electron Beam Tomography (EBT)
Robust and proven CT coronary imaging Low
Radiation (0.7-1.1 mSev) e-Speed 1.5 mm slice
thickness 50 ms temporal
resolution Limitations 2 images per heart
beat Heart Rates lt 120 bpm High Calcium
Scores/Stents
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Electron Beam Tomography (EBT)
50 ms image acquisition time 1.5 mm slice
thickness
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Electron Beam CT CORONARY ANGIOGRAPHY

• 20 MINUTE PROCEDURE
• Intravenous access required
• REQUIRES 100-120 ml CONTRAST (antecubital)
• Iodinated Dye (same as cath lab)
• Breath-hold 30-40 seconds per study
• Images available within minutes, interpretation
  time 15 minutes/study

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Non-invasive Angiography (EBA)
Rasouli, AHA 2003 25
2 92 94
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Methodology for improved detection of
coronarystenoses with computed tomographic
angiography AHJ 2004

• 86 patients evaluated with cath
• EBA correctly classified 49 of 53 patients (92)
  as having at least 1 coronary stenosis.
• Overall, 103 stenoses with 50 diameter reduction
  were present, and 93 of these lesions were
  correctly detected by EBA (sensitivity 90,
  specificity 93, positive predictive value 84,
  and negative predictive value 96). Only 5 of
  vessels could not be assessed, predominantly due
  to significant calcification.

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EBA vs. MIBI

• Cardiac CT Angiography (CTA) and Nuclear
  Myocardial Perfusion Imaging (MPI)A Comparison
  in Detecting Significant Coronary Artery Disease1
• Matthew J. Budoff, MD, - Acad Rad

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EBA vs. MIBI

• EBA demonstrated significant higher sensitivity
  than MPI (95 vs. 81, P .05).
• EBA demonstrated significantly higher specificity
  than both MPI (89 versus 78, P .04) and CAC
  (56, P .002).
• EBA also performed better in a per-vessel
  analysis (sensitivity 94, specificity 96) than
  both nuclear and CAC

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EBT C150
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EBT E-speed
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Electron Beam Angiogram
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Circumflex and OM
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EBCT ANGIOGRAM DURING A-FIB
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SOFT PLAQUE WITH EBCT
MSCT 16 slice
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Detection of SOFT Plaque with EBT or MDCT
Potential role in risk assessment? - Accuracy /
Quantification underestimates
plaque significantly (Achenbach Circ, 04) -
Reproducibility? - Progression over time? -
Prognostic value? - Additive Data to Calcium or
level of obstruction?
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Valves/Wall Motion
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Coronary Veins - Pre-BiV Pacer
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Pulmonary Veins
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Pulmonary Veins
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Carotids
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Renal Angiograms
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ALARA PRINCIPAL - Radiation

• EBT angiography - 1.1 mSv
• MSCT angiography - 9.3-11.3 mSv
• Cath 2.1-2.3 mSv
• Dose Modulation MSCT 5-8 mSv

Morin et al, Circulation 2003
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When To Use EBA even with 64 available?

• High heart rates
• Younger patients (lt40?, definitely lt30 years old)
• All pediatric applications
• CHF heart rates
• Afib patients

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Diagnostic tool with high negative predictive
value (98) if image quality is sufficient But
accuracy is lt 100 and not all vessels are
visualized
CONCLUSIONS