Diagnosis of CAD

S Richard Underwood

Professor of Cardiac Imaging

Royal Brompton Hospital &

Imperial College Faculty of Medicine

London, UK

Non-cardiac chest pain

Atypical angina

Typical angina

16%

50%

89%

Diamond & Forrester NEJM 1979;300:1350

Percent coronary disease

The history and diagnosis

0

10

20

30

40

50

60

70

99

90

8070605040

30

20

10

01

20

30

40

50

60

70

80

20

30

40

50

60

70

80

20

30

40

50

60

70

80

20

30

40

50

60

70

80

No smoker or lipids

SmokerLipids

Both

Age lineScore Probability of CAD

Score

Anginatypical 26atypical 10non-cardiac 0

MIhistory 11Q waves 12both

30

ECGST/T changes 6

Diabetes 7

Prior DB, et el. Am J Med 1983; 75: 771-780

Pre-test likelihood of CAD

hypoperfusion

diastolic dysfunction

systolic dysfunction

ECG-Changes

angina

Signs of ischaemia

Myo

card

ial pe

rfus

ion

metabolic alterations

The ischaemic cascade

Inducible Perfusion Abnormality

Stress

Rest

Detection of CAD

Sensitivity Specificity

Ex-ECG1 0.68 0.77

MPI2 0.91 0.89

1 Gianrossi R, et al. Circulation 1989; 80: 87-98

147 studies, 24074 patients

2 Maddahi J. Cardiac Imaging, edition 2. WB Saunders 1996: 971-994

9 studies, 2396 patients, qualitative and quantitative SPECT

MPS for Detection of CAD

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1988 1990 1992 1994 1996 1998 2000

Se

ns

itiv

ity

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1988 1990 1992 1994 1996 1998 2000

Sp

ecif

icit

y

Miller DD, Shaw LJ. J Nucl Cardiol 2001; 8: 616-9

Diagnosis of CAD

86%

74%

89%91% 87%

0%

20%

40%

60%

80%

100%

Sensitivity Specificity Normalcy

Metanalysis, 8964 pax ROBUST, 2652 pax

Detection of CAD

68

81

92 89 87

0%

20%

40%

60%

80%

100%

Sensitivity

77

87 8490 89

Specificity

Ex ECG (150 studies) Stress echo (14 studies)

Thallium SPECT (6 studies) MIBI SPECT(3 studies)

Tetrofosmin SPECT

Adapted from Beller GA

Bayes Theorem

ECG +

ECG -

MPI +

MPI -

Pre-test probability0 10 20 30 40 50 60 70 80 90 100

0

20

40

60

80

100

Sens Spec

ECG 0.68 0.77

MPS 0.92 0.88

Post

-test

pro

bab

ilit

y

Special circumstances in MPS

• LBBB, bifascicular block, and paced rhythm– adenosine

• chronic lung disease with pulmonary hypertension– false defects with dobutamine

• early after percutaneous coronary intervention– ?false defects in first 2-6 weeks

• balanced three vessel disease– very rare

• dilated cardiomyopathy– reversible defects possible

Artefact

• low count

• attenuation

– diaphragm

– inferior

– breast

• motion

• reconstruction

– “apical thinning”

– cold inferior wall

low count

breast

diaphragm

motion

upward creep

breast

StressStress RestRest

Conventional, backprojection Attenuation and scatter correction,iterative reconstruction

Presentation with chest painAssess• nature of symptom• risk factors• examination

Avoid unnecessary testsManage riskFor definitive exclusion of CHD, consider MPI

Primary Secondary

Investigate & treat

• Able to exercise?• Normal resting ECG?• Male?

Myocardial perfusion imaging

Medical therapyAngiography

Exercise ECG

Angina unlikely

Angina likely

Yes No

High risk Low risk

Investigation of stable angina. BCS & RCP Guidelines. Heart 1999; 81: 546-55

CAG

CAG

CAG

MPI

MPI

MPI

ECG

ACC Guidelines, stable angina

Gibbons RJ, et al. JACC 1999; 33: 2092-197

Ignoring guidelines

Southampton Chest Pain Clinic

• 1522 patients referred Dec 97 to Apr 2000 (630/yr)

• clinical management decisions by SpR with consultant supervision

Male % Female %

Ex-ECG 100 100

MPI 8 5

Angiogram 31 23

Normal angiogram 16 56

Wong Y et al. Heart 2001; 85: 149-152

Chest pain of recent onset

Assessment and investigation of recent onset chest pain or discomfort of

suspected cardiac origin

http://www.nice.org.uk/cg95NICE guidance March 2010

Contents

Acute chest pain

• 215 pages

• 88 references

• 51 recommendations

Stable chest pain

• 197 pages

• 60 references

• 42 recommendations

http://www.nice.org.uk/cg95

Diagnosis of angina

• Clinical assessment alone

• Clinical assessment with obstructive CAD on anatomical testing

• Clinical assessment with myocardial ischaemia on functional testing

Features of angina

1. Constricting discomfort in the chest, neck, shoulders, jaw or arms

2. Precipitated by physical exertion or psychological stress

3. Relieved by rest of GTN within 5 minutes

Three features = typical angina

Two features = atypical angina

One feature = non-anginal chest pain

Presentation with stable chest pain

Assessing likelihood of CAD

Gibbons RJ, et al. ACC/AHA guideline for chronic stable angina 2002

Investigation of stable chest pain

Low pre-test likelihood

If revascularisation not considered, or

If invasive angiography is not appropriate or acceptable to the person

Then, appropriate functional imaging

Appropriate

functional

imaging

Moderate pre-test likelihood

Use:

• MPS

• sEcho

• MR perfusion

• MR wall motion

The choice of imaging method

should take account of locally

available technology and expertise,

and the person and their

preferences, including any

contraindications

High pre-test likelihood

If revascularisation not considered, or

If invasive angiography is not appropriate or acceptable to the person

Then, appropriate functional imaging

Established CAD

Use:

• MPS

• sEcho

• MR perfusion

• MR wall motion

The choice of imaging method should take

account of locally available technology and

expertise, and the person and their

preferences, including any contraindications

Unhelpful investigations

• Do not use MR coronary angiography for diagnosis of CAD

• Do not use exercise ECG as the primary diagnostic test for ischaemia in people without known CAD

First line diagnostic investigations

• Likelihood <30%– Coronary calcium imaging

– CTA if CAC 1-400

– Functional imaging if CAC >400

• Likelihood 30-60%– Functional imaging

• Likelihood >60%– ICA, if clinically appropriate and revasc

considered

– Functional imaging, if ICA not appropriate

Strategy 1 2 3 4 Scint Non-scint£0

£200

£400

£600

£800

£1000

£1200

£1400

£1600 Management

Diagnosis

Total costs (CAD absent)

P < 0.001

P < 0.0001

P < 0.05

EMPIRE study. Eur Heart J 1999; 20: 157-66

N diagnostic % Normal N patients % mgmnt angiosangiograms revascularised revascularised

MPS users 43 28% 18 58%

Non-users 86 43% 21 43%

Angiography Rates

EMPIRE study. Eur Heart J 1999; 20: 157-66

EMPIRE implications for Southampton

• MPS user approach to investigation would save £65,000 per year for the same outcome

Annual Ex-ECG MPI Angio

So’ton 630 44 170

EMPIRE 253 285 92

Cost effectiveness of MPS

Where are the savings?

• patient without CAD discharged without angiography

• patient with CAD managed medically without angiography

• avoid morbidity of angiography

• revascularisation targeted more effectively at high risk patients with most to gain

Clinical Indications for Perfusion Imaging

• Diagnosis– abnormal resting ECG– unable to exercise– female– intermediate likelihood of CAD after ex-ECG

• Management– confirmation of ischaemia– prognosis– culprit lesion– viable and jeopardised myocardium– hibernating myocardium