Electron Beam Computed Electron Beam Computed Tomography in the Age of Tomography in the Age of

64 Slice CT64 Slice CT

Matthew J. Budoff, MD, FACCMatthew J. Budoff, MD, FACC

Associate Professor of MedicineAssociate Professor of Medicine

Division of CardiologyDivision of CardiologyHarbor-UCLA Medical Center, Torrance CAHarbor-UCLA Medical Center, Torrance CA

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

2.72 2

12.47

3.55

6.15

12.29

0

2

4

6

8

10

12

14

Rel

ativ

e R

isk

DM Smoke HTN <1010-100

101-400401-1000

>1000

EBT Coronary Calcium ScoreEBT Coronary Calcium Score

All Cause Mortality [NDR]All Cause Mortality [NDR]n = 10,377n = 10,377asymptomatic men and womenasymptomatic men and womenf/u = 5.0f/u = 5.0++3.5 yrs.3.5 yrs.

Shaw, Raggi et alRadiology 2003

EBT found to be independentand incremental to risk factors

All Cause Mortality in PatientsAll Cause Mortality in PatientsWithout Known CADWithout Known CAD

Prediction of Cardiac Events in AsymptomaticPrediction of Cardiac Events in AsymptomaticPatients by EBTPatients by EBT

The St. Francis Heart Study, JACC 2005The St. Francis Heart Study, JACC 2005

SFHS 3SFHS 3

0.12

0.7

2

2.4

3.3

0

0.5

1

1.5

2

2.5

3

3.5

0 > 0 > 100 > 200 > 600

Baseline EBT Calcium ScoreBaseline EBT Calcium Score

An

nu

al E

ven

t R

ate

(%)

An

nu

al E

ven

t R

ate

(%)

Calcium Score >100 vs <100

Rel

ativ

e R

isk

9.5

AnyEvent

10.7

Cor.Event

9.9

MI/SCD

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 < 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 >400 (8.7% vs. 15.0%, p=0.046 [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.

0.00 2.00 4.00 6.00 8.00 10.00 12.00

Time to Follow-up (Years)

0.75

0.80

0.85

0.90

0.95

1.00

0.00 1.00 2.00 3.00 4.00 5.00

Time to Follow-up (Years)

0.75

0.80

0.85

0.90

0.95

1.00

Near- and Long-Term Survival from 2 Cohorts – over 35,000 patients

n=10,377 n=25,257

99.4%

97.8%95.2%

90.4%

81.8%

99.4%

97.8%

94.5%

93.0%

76.9%

2=1503, p<0.0001, interaction p<o.0001

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%>1,000 81.8% 76.9% 4.9%

Cooper Clinic Study - 10,782 Patients: 3.5 year follow-up

0

10

20

30

40

50

None 1--16 17--96 97--409 >409

Ad

just

ed

Od

ds

Ra

tio

Adjusted age, history of diabetes, hypertension, elevated cholesterol, over weight

Ref

Nonfatal MI & CHD Death

2.7(0.8-9.3)

6.0(2.1-17)

9.7(3.6-26)

21.1(7.8-57)

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.

Anand EHJ 2006 – 510 Diabetics

MESA Study – 6,814 Patients: 3.5 year follow-up

0

10

20

30

40

50

None 1-100 100-300 >300

Ha

zard

Ra

tio

Fully adjusted – Detrano et al– ACC Abstract - JACC March 07

Ref

Nonfatal MI & CHD Death

2.7(0.8-9.3)

6.0(2.1-17)

9.7(3.6-26)

21.1(7.8-57)

Calcium Versus Framingham

0

20

40

60

80

100

Procam-Score Framingham Score Volume Score

Low Risk Intermediate Risk High Risk

n = 5

n = 27

n = 18

n = 4

n = 29

n = 17

n = 1

n = 5

n = 44

Myo

card

ial I

nfa

rcti

on

(%

)

““measurement of coronary calcium is an measurement of coronary calcium is an option for advanced risk assessment.option for advanced risk assessment.High coronary calcium scores (e.g., >75High coronary calcium scores (e.g., >75 thth percentile for age and sex) denotes percentile for age and sex) denotes advanced atherosclerosis and provides advanced atherosclerosis and provides rationale for intensified LDL-lowering rationale for intensified LDL-lowering therapy.”therapy.”

NCEP ATP-III : Noninvasive Testing - 2001NCEP ATP-III : Noninvasive Testing - 2001

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.

AHA – Circulation 2005This recommendation to measure atherosclerosis burden, in clinically selected intermediate–CAD

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.

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.

Blue Shield – February 2005

Blue Shield – February 2005

New Guidelines From AHA

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

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.

Radiology 2005; 235:723–727

Cardiac CT EquipmentRecommendations

• The availability of a multi–detector 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 multi–detector row CT, at least four detector rows are preferred for calcium scoring and at least 16 are preferred for CT coronary angiography.

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 < 120 bpm

High Calcium Scores/Stents

Electron Beam Tomography (EBT)

50 ms image acquisition time1.5 mm slice thickness

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

Number of Patients

Non-Evaluated Segments

Sensitivity Specifity

Moshage et al, Radiology 1995

20 ? 74% 100%

Schmermund et al, JACC 1998*

28 12% 83% 91%

Reddy et al, Radiology 1998

23 10% 88% 79%

Rensing et al, Circulation 1998**

37 18% 77% 94%

Achenbach et al, NEJM 1998

125 25% 92% 94%

Budoff et al, Am J Cardiol 1999

52 11% 78% 91%

Achenbach et al, Heart 2000

36 20% 92% 91%

Ropers et al, Z Kardiol 2000

118 24% 90% 82%

Lu, Invest Rad 2004 107 7% 91% 93%

Non-invasive Angiography (EBA)

Rasouli, AHA 2003 25 2% 92% 94%

Methodology for improved detection of coronary

stenoses 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.

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

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

EBT – C150

Normal dominant Right coronary artery

80% stenosis of distal LAD, after large diagonal

EBT E-speedNormal distal RCA AND PDA

Electron Beam Angiogram

Circumflex and OM

EBCT ANGIOGRAM DURING A-FIB

MSCT 16 slice

SOFT PLAQUE WITH EBCT

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?

Valves/Wall Motion

Coronary Veins - Pre-BiV Pacer

Pulmonary Veins

Pulmonary Veins

Carotids

Renal Angiograms

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

When To Use EBA even with 64 available?

• High heart rates

• Younger patients (<40?, definitely <30 years old)

• All pediatric applications

• CHF – heart rates

• Afib patients

Diagnostic tool with high negative predictive value (~98%) if image quality is sufficient

But accuracy is < 100% and not all vessels are visualized

CONCLUSIONSCONCLUSIONS