Screening for CAD: What Test to Order for Which Situation

1
Screening for CAD What Test to Order for Which
Situation

• John L. Tan, MD, PhD
• Presbyterian Hospital of Dallas

2
Estimated Annual Incidence of CV Disease
Cardiovascular Diseases 70 million
Silent Ischemia ? 3 million
Chest Pain 6 million
Stroke 0.5 million
Not Admitted 2 million
Heart Attack 1.5 million
Stroke Deaths 150,000
Unstable Angina 1 million
Wrongful Discharge 30,000
AMI Deaths 500,000
3
Available Tests

• Stress ECG
• Stress Imaging Study
• Ultra-fast CT (EBCT)
• CT Angiography
• Stress Cardiac MRI/MRA
• Coronary Angiography

4
Initial Considerations

• Symptomatic versus Asymptomatic
• Diagnosis versus Prognosis
• Assessment of Risk for CV mortality

5
Patients with Symptoms
6
Clinical Classification of Chest Pain
Typical Angina (definite)
(1) Substernal chest discomfort with a
characteristic quality and duration that is (2)
provoked by exertion or emotional stress and (3)
relieved by rest or nitroglycerin
Atypical Angina (probable)
Meets 2 of the above characteristics
Noncardiac Chest Pain
Meets one or none of the typical angina
characteristics
ACC/AHA ACP-ASIM Guidelines for Chronic Stable
Angina, 1999
7
Pretest Likelihood of CAD in Symptomatic
Patients Percent with significant CAD on
catheterization
Nonanginal Chest Pain
Atypical Angina
Typical Angina
Age, yrs
Men
Men
Women
Men
Women
Women
30-39 4 2 34 12 76 26 40-49 13 3 51 22 87 55 5
0-59 20 7 65 31 93 73 60-69 27 14 72 51 94 86
ACC/AHA ACP-ASIM Guidelines for Chronic Stable
Angina, 1999
8
Kaplan-Meier Survival in Risk Stratified Patients
Shaw, et al, AJC, 2000
9
Diagnosis and Risk Stratification of Patients
with Chest Pain
ACC/AHA ACP-ASIM Guidelines for Chronic Stable
Angina, 1999
Yes
Contraindications to stress testing?
No
Symptoms or clinical findings warranting
angiography?
Yes
Consider coronary angiography
No
No
Patient able to exercise?
Pharmacologic imaging study
Yes
Yes
Exercise imaging study
Previous coronary revascularization?
No
No
Resting ECG interpretable?
Yes
Perform exercise test
10
Exercise Testing
11
Indications for Stress Testing without an Imaging
Modality

• 1. Patients with an intermediate probability
  of CAD,
• including those with RBBB or lt1 mm resting ST-
• segment changes (Class I)
• 2. Patients with suspected vasospastic angina
  (Class IIa)
• 3. Patients with a high or low probability of
  CAD (Class IIb)
• 4. Annual TMT in asymptomatic patients with
  estimated
• annual mortality rate gt1

ACC/AHA ACP-ASIM Guidelines for Chronic Stable
Angina, 1999
12
Four-year Mortality Rates with Abnormal ETT
Effects of Severity of CAD
4-year Mortality Rates ()
Weiner, et al, JACC, 1984
13
Four-year Mortality Rates with Abnormal ETT
Effects of Exercise Capacity
4-year Mortality Rates ()
Weiner, et al, JACC, 1984
14
Clinically Useful Bench Marks of Exercise Capacity

• 1 MET Basal activity level (3.5 ml
  O2 comsumed/Kg/min
• lt 5 METs Associated with a poor prognosis
  in patients lt65 y/o
• 5 METs Marks the limit of ADLs, usual
  limit immediate post MI
• 10 METs Considered average level of
  fitness
• In patients with angina, no
  mortality benefit CABG vs
• medical Rx
• 13 METs Good prognosis in spite of any
  abnormal exercise test
• response
• 18 METs Aerobic master athelete
• 22 METs Achieved by well-trained
  competitive atheletes

15
Exercise Parameters Associated with Advanced CAD
or Poor Prognosis

• 1. Duration of ETT lt6.5 METS (lt5 METS for
  women)
• 2. Exercise HR lt120 bpm off b-blockers
• 3. Ischemic ST segment change at HR lt120 bpm or
  lt6.5
• METS
• 4. ST segment depression gt2 mm, especially in
  multiple
• leads
• 5. ST segment depression for gt6 min in
  recovery
• 6. Decrease in BP during exercise

16
Survival According to Risk Groups Based on Duke
TM Scores
Risk Group, Score of Total Survival
Mortality,
Low (5 or greater) 62 0.99 0.25 Moderate
(-10 to 4) 34 0.95 1.25 High (-10 or
less) 4 0.79 5.0
Duke TM Score Exercise time - (5 x ST
deviation) - (4 x Treadmill angina)
ACC/AHA ACP-ASIM Guidelines for Chronic Stable
Angina, 1999
17
Special Populations

• Elderly Persons
• (Age gt 65 )
• Women

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Exercise Testing of the Elderly

• Few elderly persons were included in studies
  validating the use of exercise testing (mean age
  in Duke Treadmill Score studies was 49 years old)
• The elderly have
• greater prevalence and severity of disease
• more co-morbid diseases
• increasingly sedentary lifestyle

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Prognostic Value of Treadmill Exercise Testing in
the Elderly

• Two variables are associated with cardiac events
  in the elderly
• 1. Angina with exercise
• 2. Workload achieved
• After workload was taken into account, neither
  abnormal ST-segment changes or exercise-induced
  angina was independently related to time to
  cardiac event

Ann Intern Med 132862-870, June 2000
20
The Problem with Women . . .

• Almost half the women younger than 65 year old
  with
• anginal symptoms in CASS had normal coronary
• arteriograms
• More women with inability to exercise to maximum
• aerobic capacity

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More Problems with Women . . .

• Exercise-induced ST-segment depression is less
  sensitive
• in women than men due to lower prevalence of
  severe
• CAD (22-42 of women vs 13-29 of men with
• CAD have one-vessel disease)
• Exercise ECG may also be less specific (72 vs
  79, with
• a PPVof 62 vs 85)

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. . .But it may not be that Bad
23
Probability of Significant Disease Across Duke TM
Scores
Alexander, et al, JACC, 1998
24
Meta-analysis of Exercise Testing
Number of
Sensitivity Specificity Predictive
Grouping Studies ()
() Accuracy ()
Standard exercise test 147 68
77 73 Without MI 58
67 72
69 Without workup bias 3
50 90 69 With ST depression
22 69 70
69 Without ST depression 3
67 84 75 With digoxin
15 68 74
71 Without digoxin 9
72 69 70 With LVH
15 68 69 68 Without LVH
10 72 77
74 Overall 70 80
ACC/AHA Guidelines for Exercise Testing, 1997
25
The Ischemic Ladder
Angina
ECG Changes
Systolic Dysfunction
MVO2
Diastolic Dysfunction
Time
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Stress Imaging
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Stress Imaging Studies
Stress Modalities
Imaging Modalities

• Echocardiography
• Perfusion Imaging
• Nuclear Scan
• Thallium Scan
• Sestamibi Scan
• Hybrid Scan
• MRI

• Exercise
• Dobutamine
• Adenosine
• (Persantine)

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Indications for Stress Imaging for Diagnosis

• 1. Abnormal resting ECG
• Wolff-Parkinson-White syndrome
• gt 1mm resting ST-segment depression
• LBBB
• V-paced rhythm
• 2. Previous non-diagnostic TMT
• 3. Inability to perform TMT

ACC/AHA ACP-ASIM Guidelines for Chronic Stable
Angina, 1999
29
Indications for Stress Imaging for Diagnosis

• 4. Prior re-vascularization including
  percutaneous
• interventions or CABG
• 5. Increased likelihood of a false-positive
  TMT
• Digoxin use
• Left ventricular hypertrophy
• 6. As the initial stress test in patients
  with a normal
• resting ECG

ACC/AHA ACP-ASIM Guidelines for Chronic Stable
Angina, 1999
30
Further indications for Stress Imaging for Risk
Stratification

• 1. To identify the extent, severity, and
  location of
• ischemia to determine
• - ischemic burden
• - functional significance of lesions
• 2. To assess post-MI prognosis

ACC/AHA ACP-ASIM Guidelines for Chronic Stable
Angina, 1999
31
Of Note

• Adenosine/dipyridamole perfusion imaging
  preferred in
• patients able to exercise with a V-paced rhythm
  or
• underlying LBBB (Class I vs IIb for stress
• echocardiography)

ACC/AHA ACP-ASIM Guidelines for Chronic Stable
Angina, 1999
32
Comparing Stress Echo to Perfusion Imaging
Myocardial Perfusion Imaging
Normal Ischemic Fixed
Total
Normal 137 10 7
154 Ischemic 4 47
3
54 Fixed 13 30
38
81 Total 154 87
48 289
Echocardiography
137 47 38 222/289 77 Agreement SPECT vs
Echo 87 vs 54 Ischemic regions
48 vs 81 Fixed regions
Quinones and Zoghbi
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Sensitivity and Specificity of Stress Studies
Procedure Sensitivity () Specificity ()
Exercise Test 68 77 Stress Echo
76 88 SPECT 88 77
34
Advantages of Stress Echocardiography

• 1. Higher specificity
• 2. Versatility more extensive evaluation of
• cardiac anatomy and function
• 3. Greater convenience/efficacy/availability
• 4. Lower cost

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Advantages of Stress Myocardial Perfusion Imaging

• 1. Higher technical success rate
• 2. Higher sensitivity, especially for
  one-vessel disease
• 3. Better accuracy in evaluating possible
  ischemia
• when multiple rest LV wall motion
• abnormalities are present
• 4. More extensive published database,
  especially in
• evaluation of prognosis

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Prognostic Value of a Normal Perfusion Scan
Number Mean
Annual of Patients Study Type
follow-up mortality ()
3594 Meta-analysis 29
months 0.9 473
Retrospective 30 /- 16 months
0.2 5183 Prospective 642 /-
226 day lt0.5 8411
Prospective 2.5 /- 1.5 years
lt0.4
In contrast, patients with an abnormal scan have
a 5-7 annualized serious adverse event
rate
37
Myocardial Perfusion Imaging Normal Study
38
Myocardial Perfusion ImagingAbnormal Study
post-CABG
39
Cardiac Imaging
Echo
MRI
40
Testing in Symptomatic Patients

• Exercise Test
• Probable more than we do
• Stress Echocardiogram
• Lower pre-test probablility population
• Valvular or other structural heart disease

41
Testing in Symptomatic Patients

• Stress Perfusion Scan
• Higher pre-test probability population
• Cardiac MRI
• When above unhelpful and expertise is available

42
Testing in Symptomatic Patients

• Ultra-fast CT (EBCT)
• No role in symptomatic patients
• CT Angiography
• Will play larger role with ability to image
  coronaries (Triple Rule Out)
• Coronary Angiography
• When stress testing is potentially dangerous

43
Patients without Symptoms
44
Estimated Annual Incidence of CV Disease
Cardiovascular Diseases 70 million
Silent Ischemia ? 3 million
Chest Pain 6 million
Stroke 0.5 million
Not Admitted 2 million
Heart Attack 1.5 million
Stroke Deaths 150,000
Unstable Angina 1 million
Wrongful Discharge 30,000
AMI Deaths 500,000
45
The Framingham Score for Risk Prediction
Greenland and Gaziano, NEJM, 2003
46
Elevated hs-CRP as an Independent Risk Factor
Ridker et al, NEJM, 2004
47
Elevated hs-CRP as an Independent Risk Factor
Ridker et al, NEJM, 2004
48
Available Tests

• Stress ECG
• Stress Imaging Study
• Ultra-fast CT (EBCT)
• CT Angiography
• Stress Cardiac MRI/MRA
• Coronary Angiography

49
Coronary Calcium Scoring
Greenland and Gaziano, NEJM, 2003
50
Coronary Calcium Scoring

• Meta-analysis
• Sensitivity of 80-92
• Specificity of 40-51
• High prevalence of unexpected, incidental
  noncardiac findings

51
Sensitivity and Specificity of CAD Studies
Procedure Sensitivity () Specificity ()
Exercise Test 68 77 Stress Echo
76 88 SPECT 88 77 EBCT
80-90 40-50
52
Incremental Value of Non-invasive Testing to Risk
Assessment
Low Risk lt10 Interm Risk 10-20 High Risk gt20
Greenland and Gaziano, NEJM, 2003
53
Incremental Value of Coronary Calcium Scoring to
Risk Assessment
Greenland et al, JAMA, 2004
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Greenland and Gaziano, NEJM, 2003