Diagnosis of CAD S Richard Underwood Professor of Cardiac Imaging Royal Brompton Hospital & Imperial College Faculty of Medicine London, UK
The history and diagnosis 89% Non-cardiac chest pain 50% Atypical angina Typical angina 16% Diamond & Forrester NEJM 1979;300:1350 Percent coronary disease
Pre-test likelihood of CAD Score Probability of CAD Age line Score Angina typical 26 atypical 10 non-cardiac 0 MI history 11 Q waves 12 both 30 ECG ST/T changes 6 70 60 50 40 30 20 10 99 90 80 70 60 50 40 30 20 10 01 80 70 60 50 40 30 20 80 80 80 70 70 70 60 60 60 50 50 50 40 30 40 40 20 30 30 20 20 Both Smoker Lipids Diabetes 7 0 No smoker or lipids Prior DB, et el. Am J Med 1983; 75: 771-780
Myocardial perfusion The ischaemic cascade hypoperfusion metabolic alterations diastolic dysfunction systolic dysfunction ECG-Changes angina Signs of ischaemia
Inducible Perfusion Abnormality Stress Rest
Detection of CAD Sensitivity Specificity Ex-ECG 1 0.68 0.77 MPI 2 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
Sensitivity Specificity MPS for Detection of CAD 100% 90% 80% 70% 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1988 1990 1992 1994 1996 1998 2000 60% 50% 40% 30% 20% 10% 0% 1988 1990 1992 1994 1996 1998 2000 Miller DD, Shaw LJ. J Nucl Cardiol 2001; 8: 616-9
Diagnosis of CAD Metanalysis, 8964 pax ROBUST, 2652 pax 100% 80% 86% 91% 74% 87% 89% 60% 40% 20% 0% Sensitivity Specificity Normalcy
Detection of CAD 100% 80% 68 81 92 89 87 77 87 84 90 89 60% 40% 20% 0% Sensitivity Ex ECG (150 studies) Thallium SPECT (6 studies) Tetrofosmin SPECT Specificity Stress echo (14 studies) MIBI SPECT(3 studies) Adapted from Beller GA
Post-test probability Bayes Theorem 100 80 ECG + ECG - MPI + MPI - 60 40 Sens Spec ECG 0.68 0.77 MPS 0.92 0.88 20 0 0 10 20 30 40 50 60 70 80 90 100 Pre-test probability
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 upward creep breast motion breast diaphragm
Stress Rest Stress Rest Conventional, backprojection Attenuation and scatter correction, iterative reconstruction
Angina unlikely Presentation with chest pain Assess nature of symptom risk factors examination Angina likely Avoid unnecessary tests Manage risk For definitive exclusion of CHD, consider MPI Yes Primary Able to exercise? Normal resting ECG? Male? Secondary Investigate & treat No High risk Exercise ECG Angiography Myocardial perfusion imaging Low risk Medical therapy Investigation of stable angina. BCS & RCP Guidelines. Heart 1999; 81: 546-55
ACC Guidelines, stable angina Ignoring guidelines CAG MPI ECG MPI CAG MPI CAG Gibbons RJ, et al. JACC 1999; 33: 2092-197
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 NICE guidance March 2010 http://www.nice.org.uk/cg95
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
Total costs (CAD absent) 1600 P < 0.0001 Management 1400 Diagnosis 1200 1000 800 P < 0.05 P < 0.001 600 400 200 0 Strategy 1 2 3 4 Scint Non-scint EMPIRE study. Eur Heart J 1999; 20: 157-66
Angiography Rates N diagnostic % Normal N patients % mgmnt angios angiograms revascularised revascularised MPS users 43 28% 18 58% Non-users 86 43% 21 43% EMPIRE study. Eur Heart J 1999; 20: 157-66
EMPIRE implications for Southampton Annual Ex-ECG MPI Angio So ton 630 44 170 EMPIRE 253 285 92 MPS user approach to investigation would save 65,000 per year for the same outcome
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