Harvey S Hecht MD

1
EBCT no consensus at all

• Harvey S Hecht MD
• Director, Cardiac Imaging
• Director, Atherosclerosis Detection and
  Preventive Treatment Center
• Arizona Heart Institute
• Phoenix, AZ

2
EBCT
Screening for cardiovascular disease

• Electron beam computed tomography (EBCT or EBT)
  is a screening tool for cardiovascular disease.
• The recently published American College of
  Cardiology/American Heart Association consensus
  document recommended
• that EBCT not be used as an early screen for
  coronary artery disease
• that the test should not be made available to
  asymptomatic people in the general population
  without a physicians request

ORourke RA, et al. Circulation 2000102126-140
ORourke RA, et al. J Am Coll Cardiol
200036(1)326-40
3
Consensus document
Fundamental misunderstanding

• Although EBCT was not designed to detect
  obstructive coronary disease, the consensus panel
  emphasized
• the high false-positive rate for prediction of
  obstructive disease
• the inaccuracy of EBCT in predicting obstructive
  coronary artery disease, suggesting that it leads
  to unnecessary angiography and stress testing

4
Non-contrast EBCT scans
The base of the heart
No calcification
Severe calcification
LAD
PA
Ao
LA
LCX
Left Main
5
Prevention vs intervention

• EBCT is about prevention not intervention.
• EBCT can detect coronary disease at its earliest
  stages by detecting calcified plaque in
  asymptomatic people.
• Aggressive preventive techniques can keep people
  identified as high risk out of the
  catheterization laboratory.
• The discovery of obstructive disease as a result
  of EBCT testing is an incidental finding.
• For detecting calcified plaque, EBCT is
  unparalleled in its power.

6
Overlooked paper
Prognostic value of EBCT supported

• Annual event rate in asymptomatic people
• 0.11 per year for people with a calcium score of
  0
• 2.1 per year for people with a calcium score of
  199
• 4.1 per year for people with a calcium score of
  100400
• 4.8 per year for people with a calcium score
  gt400
• People with a score gt400 are 45 times more likely
  to suffer a cardiac event in the next 3 years
  than people with a score of 0

Raggi P, et al. Circulation 2000101850-855
7
EBCT supported
Use in asymptomatic patients

• Group A 172 patients underwent EBCT imaging
  within 60 days of suffering an unheralded
  myocardial infarction.
• Group B 632 patients screened by EBCT were
  followed for a mean of 327 months for the
  development of acute myocardial infarction or
  cardiac death.
• The mean patient age (538 vs 529 years) and
  prevalence of coronary calcification (96 each)
  were similar in the 2 groups.

Raggi P, et al. Circulation 2000101850-855
8
EBCT supported
Results
Raggi P, et al. Circulation 2000101850-855
9
Heart disease
Detecting symptoms

• For more than 300 000 people every year, the
  first symptom of heart disease is the last
  symptom.
• We know that 2/3 of heart attacks occur in people
  who have less than a 50 narrowing, which is
  undetectable by any kind of stress test.
• Narrowing of less than 50 is only detectable by
  EBCT.
• The incidence cardiac events without any coronary
  calcium in the arteries is no more than 5.

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Calcified plaque

• Calcified plaque is present in 95 of people who
  have a cardiac event.
• The likelihood of having a cardiac event is much
  greater among people who have more plaque than
  among those who have less plaque.

11
The calcium scale

• The calcium scale is a linear scale with 4
  calcium score categories
• 0 no calcification
• 199 mild calcification
• 100400 moderate calcification
• gt400 severe calcification
• As the amount of calcium increases, the
  likelihood of an event increases, as does the
  likelihood of having obstructive disease.

12
EBCT vs stress testing
Detecting obstructive CAD

• Study design
• 97 patients with symptoms suggestive of coronary
  artery disease underwent technetium stress
  testing, treadmill-ECG, and EBCT coronary
  scanning within 3 months of coronary angiography
  for the evaluation of chest pain.
• Study conclusions
• EBCT has a higher diagnostic ability than either
  treadmill-ECG or technetium-stress for the
  detection of obstructive angiographic CAD.
• EBCT is an accurate and noninvasive alternative
  to traditional stress testing for the detection
  of obstructive CAD in symptomatic patients.

Shavelle DM, et al. J Am Coll Cardiol
200036(1)32-38
13
The ability of each test to predict obstructive
angiographic CAD
EBCT vs stress testing
Results
Shavelle DM, et al. J Am Coll Cardiol
200036(1)32-38
14
The calcium score
An absolute measure

• The calcium score is a measure of the amount of
  calcified plaque, which is linearly related to
  the total plaque burden.
• If there is a small amount of calcified plaque,
  there is a small amount of total plaque if there
  is a large amount of calcified plaque, there is a
  large amount of total plaque.
• The more calcified plaque there is, the more
  likely there is to be obstructive coronary
  disease.
• An asymptomatic patient would never go directly
  from an EBCT test to the catheterization
  laboratory they would first undergo a stress
  test.

15
Follow-up testing

• EBCT testing will not lead to unnecessary
  testing in fact, the use of EBCT testing to
  stratify patients will decrease costs by
  preventing unnecessary testing.
• Calcium score gt400A patient whose calcium score
  is gt400 should have a nuclear stress test.
• Calcium score lt400An asymptomatic patient whose
  score is lt400 does not need a nuclear stress test
  because the likelihood of having a positive test
  is no more than 10.
• Calcium score lt100The likelihood of a patient
  with a calcium score lt100 having a positive
  stress test is 12 at most.

16
The vulnerable patient
Calcified vs noncalcified plaque

• Myocardial infarctions result from the rupture of
  a vulnerable plaque, and that vulnerable portion
  of the plaque is often not the calcified portion.
  
• Although EBCT does not quantify soft,
  noncalicified plaque, where there is calcified
  plaque, there is almost invariably associated
  soft plaque.
• EBCT may not identify the vulnerable portion of
  the coronary artery that is going to rupture, but
  it does identify the vulnerable person.

17
The calcium percentile
A relative measure

• The calcium percentile normalizes the calcium
  score against people of the same age and sex.
• A 70-year-old man with a calcium percentile of 60
  would be in the 20th percentile less plaque
  than 80 of men in that age group, and more
  plaque than 19.
• A 35-year-old man with a calcium percentile of 60
  would be in the 95th percentile less plaque
  than 5 of men in that age group, and more plaque
  than 94.
• An assessment of risk based solely on the amount
  of plaque blocking the artery is not an accurate
  assessment of risk.

18
Score vs percentile

• The calcium score an index of the amount of
  plaque
• The calcium percentile an indication of how
  premature that plaque is
• These 2 elements will affect decisions about
  whether or not to proceed to a stress test and
  how vigorously to treat the cholesterol.

19
Cholesterol values
Poorly predictive of risk

• Cholesterol values are very poorly predictive of
  the presence or amount of plaque.
• Some people with normal cholesterol levels are in
  fact at extraordinarily high risk.
• EBCT is exponentially more accurate in
  identifying patients who are at risk than
  standard cholesterol guidelines are.

20
Framingham risk score
You are as old as your arteries

• The biggest contribution to the Framingham risk
  score is age, but chronological age is different
  than physiological age.
• A 50-year-old can have the coronary arteries of
  an 80-year-old and, conversely, an 80-year-old
  can have the coronary arteries of a 50-year-old.
• To assign an arbitrary risk to a patient simply
  because of their age totally ignores individual
  variation.
• The EBCT calcium score and calcium percentile can
  be used to modify the contribution that age makes
  to the Framingham risk score.

Grundy SM. Am J Cardiol 199983(10)1455-1457
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Risk scores
Individual variations

• Any general score is based on mean values derived
  from large groups of patients.
• An EBCT test will tell precisely how much
  calcified plaque a person has and where that
  person stands in relation to other people of the
  same age.
• Rather than extrapolating a number from a
  population of thousands, the EBCT represents
  individual risk.

22
Healthcare in the US
WHO report

• The US health system spends a higher portion of
  its gross domestic product than any other country
  but ranks 37 out of 191 countries according to
  its performance.
• The World Health Report 2000 Health systems
  improving performance
• According to the AHA, the cost of cardiac disease
  in the US is 280 billion per year.
• In the US, disease is treated, not prevented.
• Identifying patients who are at risk and taking
  preventive measures will lower overall healthcare
  costs.

Geneva, Switzerland World Health Organization
2000
23
EBCT for and against

• Arguments against EBCT
• To screen a large population with EBCT would be
  very costly to insurance companies and Medicare.
• By making EBCT available as a routine screen,
  millions of people who were unaware they were at
  risk will be uncovered these people will then
  require expensive treatment.
• Arguments for EBCT
• As soon as EBCT is approved as a routine screen
  and is implemented on a national level, the cost
  will plummet mammography is now much less
  expensive than when it first came out the same
  will happen with EBCT.

24
Cost of EBCT
Short term vs long term

• The long-term view
• Giving patients with high calcium scores stress
  testing may then lead to angiography, stenting,
  or bypass surgery all costly propositions.
• But, by preventing coronary events and saving
  lives, the cost to society in terms of lives and
  productivity lost as a result of cardiac disease
  will be reduced.
• The short-term view
• Average duration of enrolment in one HMO is 3
  years the person currently in one HMO may be a
  another HMO when a future coronary event occurs.
• It is a common pool of patients in this country
  and they have to be treated as such.

25
The future of EBCT
Cost effective in the long term

• The cost effectiveness of the longer-range view
  will eventually be appreciated by the insurance
  companies.
• Scientific data, which are emerging on a monthly
  basis, will confirm the value of EBCT it will be
  universally incorporated as a screening tool in
  the next consensus statement
• Public pressure will call for universal access to
  EBCT it will no longer be available only to
  those who can pay for it.

26
Advertising EBCT
Getting the message out

• Advertising is currently the most effective way
  to get the information out to the public the
  most responsive segment of the population
• Physicians may not be aware of the benefits of
  EBCT and therefore may not order it as a routine
  screening test.
• All advertising will cease as soon as the cost of
  EBCT is fully covered by the insurance companies.

27
Evidence-based medicine
Waiting for long-term results

• Scientific data supporting the use of EBCT are
  appearing in all the major peer-reviewed
  journals, but there is currently only 1 long-term
  EBCT study planned and it has design flaws.
• There are no evidence-based data that
  angioplasty, stenting, bypass surgery save lives
  or decrease coronary events.
• We cant afford to wait until stringent,
  evidence-based data are available.
• 8 times as many women die every year from
  coronary disease as die from breast cancer
• more women than men die on an annual basis of
  coronary disease