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
Women
Men
Women
Men
Women
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 <1 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 >1%
ACC/AHA ACP-ASIM Guidelines for Chronic Stable Angina, 1999

12. Four-year Mortality Rates with Abnormal ETT: Effects of Severity of CAD
Weiner, et al, JACC, 1984

13. Four-year Mortality Rates with Abnormal ETT: Effects of Exercise Capacity
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
< 5 METs Associated with a poor prognosis in patients <65 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 <6.5 METS (<5 METS for women)
2. Exercise HR <120 bpm off b-blockers
3. Ischemic ST segment change at HR <120 bpm or <6.5
METS
4. ST segment depression >2 mm, especially in multiple
leads
5. ST segment depression for >6 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)
Moderate (-10 to 4)
High (-10 or less)
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 > 65 )
Women

18. 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

19. 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 132: , 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

21. 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%)

22. . . .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
Without MI
Without workup bias
With ST depression
Without ST depression
With digoxin
Without digoxin
With LVH
Without LVH
Overall ~ ~80
ACC/AHA Guidelines for Exercise Testing, 1997

25. The “Ischemic Ladder” MVO2 Time Angina ECG Changes Systolic
Dysfunction
MVO2
Diastolic
Dysfunction
Time

26. Stress Imaging

27. Stress Imaging Studies
Stress Modalities
Imaging Modalities
Echocardiography
Perfusion Imaging
Nuclear Scan
Thallium Scan
Sestamibi Scan
Hybrid Scan
MRI
Exercise
Dobutamine
Adenosine
(Persantine)

28. Indications for Stress Imaging for Diagnosis
Abnormal resting ECG
Wolff-Parkinson-White syndrome
> 1mm resting ST-segment depression
LBBB
V-paced rhythm
Previous non-diagnostic TMT
Inability to perform TMT
ACC/AHA ACP-ASIM Guidelines for Chronic Stable Angina, 1999

29. Indications for Stress Imaging for Diagnosis
Prior re-vascularization including percutaneous
interventions or CABG
Increased likelihood of a false-positive TMT
Digoxin use
Left ventricular hypertrophy
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
To identify the extent, severity, and location of
ischemia to determine
- ischemic burden
- functional significance of lesions
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
Ischemic
Fixed
Total
Echocardiography
= 222/ % Agreement
SPECT vs Echo vs 54 Ischemic regions
48 vs 81 Fixed regions
Quinones and Zoghbi

33. Sensitivity and Specificity of Stress Studies
Procedure Sensitivity (%) Specificity (%)
Exercise Test
Stress Echo
SPECT

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

35. Advantages of Stress Myocardial Perfusion Imaging
Higher technical success rate
Higher sensitivity, especially for one-vessel disease
Better accuracy in evaluating possible ischemia
when multiple rest LV wall motion
abnormalities are present
More extensive published database, especially in
evaluation of prognosis

36. Prognostic Value of a Normal Perfusion Scan
Number Mean Annual
of Patients Study Type follow-up mortality (%)
Meta-analysis months
Retrospective /- 16 months
Prospective /- 226 day <0.5
Prospective /- 1.5 years <0.4
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 Imaging Abnormal 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
Stress Echo
SPECT
EBCT

52. Incremental Value of Non-invasive Testing to Risk Assessment
Low Risk <10%
Interm Risk 10-20%
High Risk >20%
Greenland and Gaziano, NEJM, 2003

53. Incremental Value of Coronary Calcium Scoring to Risk Assessment
Greenland et al, JAMA, 2004

54. Greenland and Gaziano, NEJM, 2003