to stress or not to stress ?
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To Stress or not to stress ?. Karam Paul MS, MD, MBA, FACC Community Heart and Vascular. Cardiac stress testing - learning objectives. ►Know why to undertake a stress test ►Know who should have one ►Know how it is performed ►Understand the limitations ►Understand which to choose - PowerPoint PPT PresentationTRANSCRIPT
TO STRESS OR NOT TO STRESS ?
Karam Paul MS, MD, MBA, FACCCommunity Heart and Vascular
Cardiac stress testing - learning objectives
►Know why to undertake a stress test ►Know who should have one ►Know how it is performed ►Understand the limitations ►Understand which to choose ►Know what to do with the result
Cardiac stress testing
Why do a stress test?
Aims of stress testing ►Elicit abnormalities not present at rest
►Estimate functional capacity
►Estimate prognosis
►Likelihood of coronary artery disease ►Extent of coronary artery disease
►Effect of treatment
Cardiac stress testing
Who should have one?
Diagnostic test
►Bayes’ Theorem
►Consider the ‘pre-test risk’
►Sensitivity & specificity of the test
►Post-test probability of CAD ►Diagnostic power of EST is maximal when the pre-test probability is intermediate.
Risk assessment ►Pre-existing coronary artery disease
►Diabetes
►Hypertension
►Smoking history
►Family history ►Renal disease
Consider other risk factors
Pre-existing coronary artery disease ►Diabetes ►Hypertension ►Hyperlipidemia ►Smoking history ►Family history ►Renal disease
Consider other risk factors
►Pre-existing coronary artery disease
►Diabetes ►Hypertension ►Hyperlipidemia ►Smoking history ►Family history ►Renal disease
Valvular heart disease
Rhythm disorders
Contraindications
Cardiac Stress Testing
How is it done?
Exercise protocol
Positive!
Measurements ►ECG
►Exercise capacity (METS – metabolic equivalent)
►Symptoms
►Blood pressure
►Heart rate response & recovery
ECG
1mm planar ST depression
3 consecutive beats
► The normal and rapid upsloping ST segment responses are normal responses to exercise. ► Minor ST depression can occur occasionally at submaximal workloads in patients with coronary disease. ► The slow upsloping ST segment pattern often demonstrates an ischemic response in patients with known coronary disease or those with a high pretest clinical risk of coronary disease. ► Downsloping ST segment depression represents a severe ischemic response. ► ST segment elevation in an infarct territory (Q wave lead) indicates a severe wall motion abnormality and, in most cases, is not considered an ischemic response.
(From Chaitman BR: Exercise electrocardiographic stress testing. In Beller GA [ed]: Chronic Ischemic Heart Disease. In Braunwald E [series ed]: Atlas of Heart Diseases. Vol 5. Chronic Ischemic Heart Disease. Philadelphia, Current Medicine, 1995, pp 2.1-2.30
T wave changes
► Influenced by: Body position Respiration Hyperventilation Drug Rx Myocardial ischemia Necrosis
► Pseudonormalisation: Usually non-diagnostic Consider ancillary imaging
METs
Heart rate response
►Peak HR > 85% of maximal predicted for age
►HR recovery >12 bpm (erect)
►HR recovery >18 bpm (supine)
Heart rate response
Prognostic value of stress testing
Parameters associated with adverse prognosis or multi-vessel disease
► Duration of symptom-limiting exercise <5 METs ► Failure to increase sBP ≥120mmHg, or a sustained decreased ≥ 10mmHg, or below rest levels, during progressive exercise ► ST segment depression ≥2mm, downsloping ST segment, starting at <5 METs, involving ≥5 leads, persisting ≥5 min into recovery ► Exercise-induced ST segment elevation (aVR excluded) ► Angina pectoris at low exercise workloads ► Reproducible sustained (>30 sec) or symptomatic ventricular tachycardia
Limitations of treadmill stress test
► Non-diagnostic ECG changes ► False positives/false negatives ► Women – false positives ► Elderly – more sensitive/less specific ► Diabetics – autonomic dysfunction ► Hypertension ► Inability to exercise ► Drugs – digoxin; anti-anginals
Non-coronary causes of ST segment depression
► Anemia ► Cardiomyopathy ► Digoxin ► Glucose load ► Hyperventilation ► Hypokalemia ► Intraventricular conduction disturbance ► Mitral valve prolapse ► Pre-excitation syndrome ► Severe aortic stenosis ► Severe hypertension ► Severe hypoxia ► Severe volume overload (aortic or mitral regurgitation) ► Sudden excessive exercise ► Supraventricular tachycardia's
Limitations of treadmill stress test
Sensitivity 68% Specificity 77%
Ancillary techniques to enhance content
Echocardiography Radionuclide imaging
Stress echocardiography
Stress echocardiography Compares pre & post: Regional contractility Overall systolic function Volumes Pressure gradients Filling pressures Pulmonary pressures Valvular function
Dobutamine stress echo
Stress echo - limitations
Factors which effect image quality:
Body habitus Lung disease Breast implants
Normal stress echocardiogram
Case 1
►54 year old bank project manager ►Exertional chest pain & dyspnea ►Ex-smoker ►TC = 6.7mmol/L ►Stress ECG – 2mm ST segment depression in 5 leads
Stress echocardiogram
Coronary angiogram
Case 2
►62 year old female
►Chest pain & dyspnea
►Treadmill exercise test – non-diagnostic sub-maximal Hypertension No ECG changes
Case 2
►Exercised 7½ minutes (9.4 METS)
►No chest pain
►ECG changes
Case 2
Case 2
Case 3
►24 year old female engineer ►Exertional dyspnea
►Palpitations
Case 3
Inducible dyspnea ►ECG partial right bundle branch block no ischemic changes
Case 3
Case 3
Case 3
Case 4
►43 year old male - airline catering ►Chest pain
►Dyspnea
Case 4
►Inducible dyspnea ►Non-specific T wave changes ►No ST segment shift ►Global deterioration in left ventricular function
Case 4
Case 4
Case 4
Nuclear SPECT imaging ►Radio-tracer injection ►Isotopes: Thallium-201 Technetium 99m (sestamibi)
►Myocardial uptake ►Photon emission captured by gamma camera ►Rest & redistribution phases ►Pharmacologic protocols available ►Digital presentation
Nuclear SPECT imaging
Nuclear SPECT imaging
Nuclear SPECT imaging
Nuclear SPECT imaging
Reversible inferior wall defect
Milder reversible inferior wall defect
Limitations of nuclear SPECT imaging
►Time-consuming
►Artifacts ►Balanced ischemia ►Radiation
Limitations of nuclear SPECT imaging
Normal apical thinning.
Limitations of nuclear SPECT imaging
A. Breast attenuation B. Anterior ischemia
Limitations of nuclear SPECT imaging
Limitations of nuclear SPECT imaging
►Risk of iatrogenic malignancy
►Linear no-threshold model ►Consider: age gender background
Limitations of nuclear SPECT imaging
Einstein, A. J. et al. Circulation 2007;116:1290-1305
MRI cardiac stress test
Useful for: ►Patients unable to exercise ►ECG uninterpretable ►Unsuitable for DSE
And…. ►No radiation
But… ►Not currently available
Question ►45 year old diabetic man
►Anterior chest discomfort with exertion ►Exercised for 2 mins 30 secs (4.6 METs) ►95% maximal predicted heart rate
►Mild chest pain
►BP increased from baseline to 180/80mmHg
►1mm ST depression in leads II, III, aVF, V4-6
Which is true?
1. Pre-test risk is intermediate 2. Post-test probability for cardiac events is high 3. The ECG changes are non-diagnostic 4. The ECG changes are false-positive in the setting of hypertension 5. Chest pain is not a useful symptom in diabetics
Answer
1. Pre-test risk is intermediate 2. Post-test probability for cardiac events is high 3. The ECG changes are non-diagnostic 4. The ECG changes are false-positive in the setting of hypertension 5. Chest pain is not a useful symptom in diabetics
Remember…
Remember…
Parameters associated with adverse prognosis or multi-vessel disease
► Duration of symptom-limiting exercise <5 METs ► Failure to increase sBP ≥120mmHg, or a sustained decreased ≥ 10mmHg, or below rest levels, during progressive exercise ► ST segment depression ≥2mm, downsloping ST segment, starting at <5 METs, involving ≥5 leads, persisting ≥5 min into recovery ► Exercise-induced ST segment elevation (aVR excluded) ► Angina pectoris at low exercise workloads ► Reproducible sustained (>30 sec) or symptomatic ventricular tachycardia
When ordering a stress test consider…
►Pre-test risk of disease
►Sensitivity & specificity of the test
►Value of supplementary data
►AND JUST ONE MORE TIP……..
MRI cardiac stress test
Cardiac stress testing
So….which one to choose?
What to do with the result?
►Remember Bayes’ theorem
►Consider the pre-test risk
►Be aware of the sensitivity & specificity of the test
►Apply the post test probability
CT Calcium score
►Correlates with presence & extent of CAD ►Strong negative predictive value
►Cannot predict functional significance
►Higher scores can predict events
►Recommended for asymptomatic with intermediate risk
CT Calcium score
Calcification of the left anterior descending coronary artery (large arrow) and left circumflex coronary artery (small arrow).
CT Calcium score
Score description RR 0 nil 1 – 99 mild 1.9 100 – 399 moderate 4.3 400 – 999 severe 7.2 >1000 extensive 10.8
CT Calcium score
► Indicated – asymptomatic with intermediate risk
► Not for low risk/population screening ► High risk – use current guidelines
► Do not reduce Rx if intermediate risk & ‘0’ score
CT coronary angiography
►2-dimensional & 3-dimensional reconstructions
►Relies on slow, regular heart rate
►High negative predictive value (‘rule out’ ability)
CT coronary angiography - limitations
►Lower positive predictive value (over-estimation tendency)
►Grading of stenosis limited
►Does not evaluate functional significance
►Radiation exposure
CT coronary angiography
►Role not yet clearly defined
►Potential for those with intermediate likelihood of disease: Where stress testing not possible Stress test equivocal/uninterpretable Acute chest pain/no ECG changes/normal enzymes
►Role in anomalous anatomy
CT coronary angiography