Screening for CAD: What Test to Order for Which Situation John L. Tan, MD, PhD Presbyterian Hospital...

Screening for CAD: What Test to Order for Which

Situation

John L. Tan, MD, PhD

Presbyterian Hospital of Dallas

Estimated Annual Incidence of CV Disease

Cardiovascular Diseases70 million

Stroke0.5 million

Stroke Deaths150,000

Silent Ischemia? 3 million

AMI Deaths500,000

Chest Pain6 million

Not Admitted2 millionHeart Attack

1.5 million

Unstable Angina1 million Wrongful Discharge

30,000

Available Tests

• Stress ECG

• Stress Imaging Study

• Ultra-fast CT (EBCT)

• CT Angiography

• Stress Cardiac MRI/MRA

• Coronary Angiography

Initial Considerations

• Symptomatic versus Asymptomatic

• Diagnosis versus Prognosis

• Assessment of Risk for CV mortality

Patients with Symptoms

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 PainMeets one or none of the typical angina characteristics

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

Pretest Likelihood of CAD in Symptomatic Patients: Percent with significant CAD on catheterization

30-39 4 2 34 12 76 26

40-49 13 3 51 22 87 55

50-59 20 7 65 31 93 73

60-69 27 14 72 51 94 86

Age, yrs Men MenWomen Men Women Women

NonanginalChest Pain

AtypicalAngina

TypicalAngina


Kaplan-Meier Survival in Risk Stratified Patients

Shaw, et al, AJC, 2000

Contraindications to stress testing?

Symptoms or clinical findings warranting angiography?

Patient able to exercise?

Resting ECG interpretable?

Pharmacologic imaging study

Previous coronary revascularization?

Perform exercise test

Exercise imaging study

Consider coronary angiography

Diagnosis and Risk Stratification of Patients with Chest Pain

No

No

No

No

Yes

Yes

Yes

Yes

Yes

No


Exercise Testing

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

Four-year Mortality Rates with Abnormal ETT: Effects of Severity of CAD

5.5

9.5

13.5

0

2

4

6

8

10

12

14 1-Vessel2-Vessel3-Vessel

4-ye

ar M

orta

lity

Rat

es (

%)

Weiner, et al, JACC, 1984

Four-year Mortality Rates with Abnormal ETT: Effects of Exercise Capacity

0

18 20

47

0

5

1015

20

25

3035

40

45

50STAGE 5STAGE 2-4STAGE 1STAGE <1

4-ye

ar M

orta

lity

Rat

es (

%)

Weiner, et al, JACC, 1984

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

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 -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

Survival According to Risk Groups Based on Duke TM Scores

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

Risk Group, Score % of Total Survival Mortality, %

Duke TM Score = Exercise time - (5 x ST deviation) - (4 x Treadmill angina)


Special Populations

• Elderly Persons(Age > 65 )

• Women

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

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 132:862-870, June 2000

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 maximumaerobic capacity

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%)

. . .But it may not be that Bad

Probability of Significant Disease Across Duke TM Scores

Alexander, et al, JACC, 1998

Meta-analysis of Exercise Testing

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

Number of Sensitivity Specificity Predictive Grouping Studies (%) (%) Accuracy (%)

ACC/AHA Guidelines for Exercise Testing, 1997

The “Ischemic Ladder”M

VO

2

DiastolicDysfunction

SystolicDysfunction

ECGChanges

Angina

Time

Stress Imaging

Stress Imaging Studies

• Exercise• Dobutamine• Adenosine• (Persantine)

• Echocardiography• Perfusion Imaging

– Nuclear Scan

– Thallium Scan

– Sestamibi Scan

– Hybrid Scan

• MRI

Stress Modalities Imaging Modalities

Indications for Stress Imaging for Diagnosis

1. Abnormal resting ECG

Wolff-Parkinson-White syndrome> 1mm resting ST-segment

depressionLBBBV-paced rhythm

2. Previous non-diagnostic TMT

3. Inability to perform TMT ACC/AHA ACP-ASIM Guidelines for Chronic Stable Angina, 1999

Indications for Stress Imaging for Diagnosis

4. Prior re-vascularization including percutaneous interventions or CABG

5. Increased likelihood of a false-positive TMTDigoxin useLeft ventricular hypertrophy

6. As the initial stress test in patients with a normal resting ECG


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


Of Note

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


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

Ec h

o car

d io g

r aph

y

137 + 47 + 38 = 222/289 77% AgreementSPECT vs Echo 87 vs 54 Ischemic regions 48 vs 81 Fixed regions Quinones and Zoghbi

Sensitivity and Specificity of Stress Studies

Procedure Sensitivity (%) Specificity (%)

Exercise Test 68 77

Stress Echo 76 88

SPECT 88 77

Advantages of Stress Echocardiography

1. Higher specificity

2. Versatility: more extensive evaluation ofcardiac anatomy and function

3. Greater convenience/efficacy/availability

4. Lower cost

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

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 <0.5

8411 Prospective 2.5 +/- 1.5 years <0.4

In contrast, patients with an abnormal scan have a 5-7% annualized serious adverse event rate

Myocardial Perfusion Imaging

Normal Study

Myocardial Perfusion ImagingAbnormal Study post-CABG

Cardiac Imaging

Echo MRI

Testing in Symptomatic Patients

• Exercise Test

– Probable more than we do

• Stress Echocardiogram

– Lower pre-test probablility population– Valvular or other structural heart disease


• Stress Perfusion Scan– Higher pre-test probability population

• Cardiac MRI

– When above unhelpful and expertise is

available



– No role in symptomatic patients

• CT Angiography– Will play larger role with ability to image

coronaries (Triple Rule Out)


– When stress testing is potentially dangerous

Patients without Symptoms

Estimated Annual Incidence of CV Disease

Cardiovascular Diseases70 million

Stroke0.5 million

Stroke Deaths150,000

Silent Ischemia? 3 million

AMI Deaths500,000

Chest Pain6 million

Not Admitted2 millionHeart Attack

1.5 million

Unstable Angina1 million Wrongful Discharge

30,000

The Framingham

Score for Risk

Prediction

Greenland and Gaziano, NEJM, 2003

Elevated hs-CRP as an Independent Risk Factor

Ridker et al, NEJM, 2004

Available Tests

• Stress ECG

• Stress Imaging Study


• CT Angiography

• Stress Cardiac MRI/MRA


Coronary Calcium Scoring


Coronary Calcium Scoring

• Meta-analysis:– Sensitivity of 80-92%– Specificity of 40-51%

• High prevalence of unexpected, incidental noncardiac findings

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

Incremental Value of Non-

invasive Testing to Risk

Assessment

Low Risk <10%Interm Risk 10-20%High Risk >20%


Incremental Value of Coronary Calcium Scoring to Risk Assessment

Greenland et al, JAMA, 2004

Screening for CAD: What Test to Order for Which Situation John L. Tan, MD, PhD Presbyterian Hospital...

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