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EBCT: no consensus at all

EBCT: no consensus at all. Harvey S Hecht MD Director, Cardiac Imaging Director, Atherosclerosis Detection and Preventive Treatment Center Arizona Heart Institute Phoenix, AZ. EBCT. Screening for cardiovascular disease.

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EBCT: no consensus at all

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  1. EBCT: no consensus at all Harvey S HechtMD 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 physician’s request O’Rourke RA, et al. Circulation 2000;102:126-140 O’Rourke RA, et al. J Am Coll Cardiol 2000;36(1):326-40

  3. Consensus document Fundamental misunderstanding • Although EBCT wasnot 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 angiographyand stress testing

  4. Non-contrast EBCT scans The base of the heart Severe calcification No 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 1–99 • 4.1% per year for people with a calcium score of 100–400 • 4.8% per year for people with a calcium score >400 • People with a score >400 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 2000;101:850-855

  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 32±7 months for the development of acute myocardial infarction or cardiac death. • The mean patient age (53±8 vs 52±9 years) and prevalence of coronary calcification (96% each) were similar in the 2 groups. Raggi P, et al. Circulation 2000;101:850-855

  8. EBCT supported Results Raggi P, et al. Circulation 2000;101:850-855

  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%.

  10. 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 • 1–99: mild calcification • 100–400: moderate calcification • >400: 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 2000;36(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 2000;36(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 >400A patient whose calcium score is >400 should have a nuclear stress test. • Calcium score <400An asymptomatic patient whose score is <400 does not need a nuclear stress test because the likelihood of having a positive test is no more than 10%. • Calcium score <100The likelihood of a patient with a calcium score <100 having a positive stress test is 1%–2% 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 1999;83(10):1455-1457

  21. 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 can’t 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

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