exercise stress test apiwan nuttamonwarakul the supreme patriarch center on aging ministry of public...
TRANSCRIPT
Exercise Stress TestExercise Stress Test
Apiwan NuttamonwarakulThe Supreme Patriarch Center on Aging
Ministry of Public Health
Objectives Review essential Exercise
Stress Test (EST) background, resources and terminology.
Describe the performance of the EST.
Describe common normal and abnormal responses to exercise testing.
Discuss interpretation of the EST.
Exercise Stress Test Essentials
Exercise Stress Testing and Family Physicians Frequency of Utilization: Estimated that 13% of family physicians
perform and interpret treadmills in their office. American Academy of Family Physicians. Facts about Family
Practice. Kansas City, Mo: American Academy of Family Physicians; 1998.
Credentialing: Recent guidelines suggest that a physician acquire 50 exercise stress tests to qualify for privileges, and should perform atleast 25/yr to maintain clinical competency. Schlant et al: Clinical competence in exercise testing: a
statement for physicians from the ACP/ACC/AHA task force on clinical privileges in cardiology. Circulation 1990;82;1884-1888.
Safety and Exercise Stress Testing The risk of death during or
immediately after an exercise test is less than or equal to 0.01%.
The risk of an acute MI during or immediately after an exercise test is less than or equal to 0.04%.
The risk of a complication requiring hospitalization is less than or equal to 0.2%.
References ACC/AHAQ Practice Guidelines
Fletcher GF et al: Exercise Standards: a statement for healthcare professionals from the American Heart Association Writing Group: Special Report. Circulation 1995;91:580-615.
ACC/AHA Guidelines for Exercise Testing. A Report of the ACC/AHA Task Force on Practice Guidelines. JACC Vol. 30 (3):260-311.
Gibbons RJ et al: ACC/AHA 2002 guideline update for exercise testing: a report of the American College of Cardiology/American heart Association Task Force on Practice Guidelines 2002. www.acc.org/clinical/guidelines
ACSM References ACSM’s Guidelines for Exercise Testing and
Prescription, Seventh Edition. ACSM’s Resource Manual for Exercise Testing
and Prescription, Seventh Edition.
The Electrocardiogram PR segment: isoelectric line
from which the J point and ST segment are measured from rest. PQ junction is the point of reference.
J Point: point that distinguishes the QRS complex from the ST segment; measuring point for ST segment depression.
ST segment: ST segment is measured relative to the PQ junction, 80 ms from the J point, or 60 ms in rates over 145 bpm.
Exercise Physiology METs: oxygen uptake is conveniently
expressed in METs; 3.5 ml O2/kg/min 1 MET=rest; 5 MET=ADLs;10 METs=
medical therapy equivalent to CABG; 18 METS=elite athlete.
Myocardial Oxygen Consumption: Double product of HRxSBP correlates with
myocardial oxygen consumption.
VO2 max: Fick Equation: VO2max = (HRmax x SV
max) x (CaO2max – CvO2max) Gold standard for aerobic fitness.
Metabolic Equivalents (METs) 1 MET = 3.5 ml O2 per kilogram of body weight
per minute
Key MET Values (part 1) 1 MET = "Basal" = 3.5 ml O2 /Kg/min
2 METs = 2 mph on level
4 METs = 4 mph on level
< 5METs = Poor prognosis if < 65; limit immediate post MI; cost of basic activities of daily living
Key MET Values (part 2) 10 METs = As good a prognosis with medical
therapy as CABS
13 METs = Excellent prognosis, regardless of other exercise responses
16 METs = Aerobic master athlete
20 METs = Aerobic athlete
Myocardial (MO2) Coronary Flow x Coronary a - VO2 difference Wall Tension (Pressure x Volume, Contractility, Stroke Work, HR) Systolic Blood Pressure x HR
Double product < 20,000 is low heart work load Double product > 29,000 indicates high heart work load
SBP should rise > 40 mmHg Drops are ominous (Exertional Hypotension) DBP should decline Angina and ST Depression usually occurs at same Double
Product in an individual** Direct relationship to VO2 is altered by beta-blockers, training,...
The Fick Equation
VO2max = (HRmax X SVmax) X (CaO2max - CvO2max)
(220 - Age)
Sinus Node Dysfunction
Drugs (e.g., B - blockers)
Genetic Factors (Heart Size)
Conditioning Factors Contractility/Afterload/Preload
Disease Factors Wall Motion/Ventricular Fxn Valve Stenosis or Regurgitation
PaO2
Hgb [ ]
SaO2
Diffusion
Ventilation
Perfusion
Skeletal Muscles
•Aerobic Enzymes•Fiber Type•Muscle Disease
Capillary Density
Performance of the Exercise Stress Test
Equipment and Protocols Equipment:
Treadmill Cycle Arm Ergometery Monitor and EKG Recorder Thallium, Echocardiography
Protocol: Maximal:
Bruce Protocol is the most commonly used test. Vigorous with the first stage commencing at 5 METs. Speed and grade is increased every three months. Generally symptom-limited; adequate tests reach 85% of MPHR.
Sub-Maximal: Tests that involve termination at a pre-determined heart rate. Post-
MI patients generally are set at 60% of MPHR, 5 METs or 120 bpm.
Which Protocol? Vast Majority (82+%) use BRUCE
So, why not you?
Treadmill Protocols
Indications ACC/AHA Guidelines for
Exercise Testing Class I: general
consensus/evidence that testing is justified.
Class II: divergence of opinion on utility. IIa in favor; IIb less evidence.
Class III: agreement that testing is not warranted.
Indications: Diagnose Obstructive CAD Class I
Adult patients (including those with RBBB and 1mm resting ST depression) with an intermediate pre-test probability of disease.
Class IIa Patients with vasospastic angina.
Class IIb Patients with a high or low pre-test probability of disease. Patients with less than 1mm ST depression and taking digoxin. Patients with LVH by voltage and less than 1mm of baseline ST
depression. Class III
WPW; paced rhythm; >1mm ST depression; LBBB.
Pre-Test Probability of CADAge Gender Typical/Definite
Angina PectorisAtypical/ProbableAngina Pectoris
Non-Anginal
Chest Pain
Asymptomatic
30-39 Males Intermediate Intermediate low (<10%) Very low (<5%)
30-39 Females Intermediate Very Low (<5%) Very low Very low
40-49 Males High (>90%) Intermediate Intermediate low
40-49 Females Intermediate Low Very low Very low
50-59 Males High (>90%) Intermediate Intermediate Low
50-59 Females Intermediate Intermediate Low Very low
60-69 Males High Intermediate Intermediate Low
60-69 Females High Intermediate Intermediate Low
High = >90% Intermediate = 10-90% Low = <10% Very Low = <5%
ACSM Recommendations for Exercise Testing Prior to Exercise Participation
CAD Risk Factors FH: MI in 1st degree male
relative before 55; female before 65.
Smoker or quit within 6 months.
Hypertension Hypercholesterolemia:
TCHOL > 200; HDL <35; LDL > 130.
Impaired fasting glucose: >110.
Obesity: BMI >30. Sedentary HDL >60 is a negative risk
factor.
CAD Signs/Symptoms Pain in the chest, neck,
jaw, arms that may be due to ischemia
SOB at rest or exertion Dizziness or syncope Orthopnea/PND Ankle edema Claudication Known heart murmur Unusual fatigue or SOB
with usual activities
ACSM Recommendations for Exercise Testing Prior to Exercise Participation
Initial ACSM Risk Stratification Low Risk: younger individuals who are
asymptomatic and have no more than one risk factor.
Moderate Risk: older or those who meet the threshold for two or more risk factors.
High Risk: individual with signs or symptoms of CAD, or known cardiovascular, pulmonary, or metabolic disease
Old versus Young Men < 45 years of age; Women < 55.
Moderate versus Vigorous Exercise Moderate: 3-6 METs, 40 to 60% maximal oxygen
uptake. Vigorous: >6 METs, or 60% maximal oxygen
uptake.
ACSM Recommendations for Exercise Testing Prior to Exercise Participation
Low Risk Moderate Risk
High Risk
Moderate Exercise
Not Necessary
Not Necessary
Recommended
Vigorous Exercise
Not Necessary
Recommended Recommended
Contraindications Absolute
Acute myocardial infarction (within 2d)
High risk unstable angina Uncontrolled arrhythmias
causing symptoms or hemodynamic compromise
Symptomatic severe aortic stenosis
Acute PE, myocarditis or pericarditis
Acute aortic dissection
Contraindications Relative
Left main coronary stenosis Moderate stenotic valvular
heart disease Electrolyte Abnormalities Severe arterial hypertension
(200/110) Tachy/Bradyarrhythmias Hypertrophic cardiomyopathy Mental or physical impairment
leading to inability to exercise adequately
High degree AV block
Special Considerations Medications
Beta blockers: blunt HR response; short acting held the day of the test; long acting held two days.
Calcium channel blockers: delay ischemia, decreasing sensitivity of the test.
Digoxin: produces abnormal ST depression with exercise.
Diuretics: may cause ST depression with hypokalemia.
Conduction Disturbances High degree AV block (Mobitz II and third
degree block) should not be tested. LBBB and WPW preclude interpretation of
ischemia and should not be tested. Special Clinical Situations
Severe arthritis/Obesity: consider pharmacologic stress testing.
Hypertension: don’t test 200/120 Q waves: in post MI pts, ST elevation can
indicate a hypokinetic ventricle.
Physician Responsibilities During the Test Patient Evaluation and Clearance
Careful history of symptoms and past medical history; typical vs. atypical.
Risk factors Family history Informed Consent
Physical Examination Vital signs Cardiovascular: murmurs, gallops Lungs
Selection of Protocol Maximal vs. Sub-Maximal Treadmill vs. Cycle
Performing the Test
Preparing the Patient Monitoring the Patient Terminating the Test Recovery of the Patient
Preparing the Patient Instructions:
No eating two hours before test; no consumption of alcohol, caffeine, or tobacco three hrs before.
Comfortable clothing. Medications determined by
functional vs. diagnostic testing. Skin Preparation
Hair shaved; abrasive rub; “tap” test.
Appropriate Blood Pressure cuff. Consent.
Preparing the Patient Pre-Test Checklist
Equipment and safety check Informed Consent Pre-test history and physical
examination Electrode skin preparation Resting ECG reviewed Standing ECG and BP Patient Demonstration Patient Questions
Monitoring the Patient Pre-Test
12 lead ECG supine and standing.
BP supine and standing. Exercise
12 lead last 15 sec of each stage.
BP and RPE at the end of each stage.
Post-Test 12 lead ECG immediately after
exercise, then every 1 to 2 minutes until return to baseline.
BP: immediately after exercise, then every 1 to 2 minutes until return to baseline.
Follow symptoms.
Borg RPE Scale 6 7 Very, very light 8 9 Very light 10 11 Fairly light 12 13 Somewhat hard 14 15 Hard 16 17 Very hard 18 19 Very, very hard 20
Terminating the Test All treadmill stress tests
should be completed to a symptom-limited endpoint, if possible.
85% of maximal predicted heart rate is required to identify a test as adequate.
Indications for Test Termination Absolute
Drop in SBP of >10 mmHg from baseline, despite increased workload, when accompanied by other ischemia
Moderate to severe angina Increasing ataxia, dizziness, or
pre-syncope Signs of poor perfusion Technical difficulties Subjects desire Sustained Vtach ST elevation in leads without
diagnostic Q waves
Indications for Test Termination Relative
Drop in SBP of >10 mmHg from baseline, despite increased workload
ST depression >2mm from baseline
Multifocal PVCs, triplets, SVT, heart block
Fatigue, shortness of breath, wheezing, leg cramps
Bundle branch block Increasing chest pain Hypertensive response
Recovery of the Patient Have the patient lie down
and continuously observe.
Auscultate for abnormal heart and lung sounds.
Monitor until clinically stable and electrocardiogram has returned to normal.
ECG changes in recovery just as ominous as those occurring during exercise.
Common Normal Responses to Exercise Testing Symptoms
Typical anginal symptoms can be produced by testing and increase the prognostic value of a test.
Symptoms, however, do not define a positive test, and define a test “suggestive of ischemia.”
Opportunity for “anginal threshold” determination and use of Borg Scale for exercise prescription.
Electrocardiographic Responses to Exercise P wave:
Superimposition of P and T; p wave may increase in inferior leads.
PR segment: Shortens and downslopes in the inferior
leads. QRS complex:
Increases in septal q waves; slight decreases in R wave amplitude; minimal shortening of interval.
J junction: Decreases with exercise; in subjects with
resting J junction elevation, this normalizes to baseline.
ST segment: Demonstrates positive upslope that returns
to baseline by 80ms. T wave:
initially a gradual decrease in amplitude. QT interval:
Rate-related shortening.
Heart Rate Normal Heart Rate Response
Increase in HR as a result of vagal tone withdrawal. Standard deviation for peak HR determination is 15 BPM.
Chronotropic Incompetence Peak heart rate less than 120 BPM. Failure to achieve 85% of age-predicted maximum.
Heart Rate Recovery
Heart Rate Recovery and Treadmill Exercise Score as Predictors of Mortality in Patients Referred for Exercise ECG Nishime EO, et al: JAMA, September 20, 2000.Vo 284, No 11, 2000.
Heart Rate Drop in Recovery vs METs 10 to 15% increase in survival per MET METS can be increased by 25% by a training
program What about Heart Rate Recovery???
Heart Rate Recovery Following the EST, patients walked for 2 minutes at 1.5
mph and at a grade of 2.5%. Heart rate recovery was the difference in heart rate at
peak exercise and one minute into recovery; 12/min or less was considered abnormal.
9454 patients were followed for a median of 5 years; 20 % had abnormal heart rate recovery; they represented 8% of deaths vs. 2%; hazard ratio of 4.16.
Heart rate recovery is an independent predictor of mortality.
Should Heart Rate Drop in Recovery be added to ET? Long known as a indicator of fitness: perhaps better for
assessing physical activity than METs Recently found to be a predictor of prognosis after
clinical treadmill testing Does not predict angiographic CAD
Studies to date have used all-cause mortality and failed to censor
Probably not more predictive than Duke Treadmill Score or METs
Studies including censoring and CV mortality needed
Blood Pressure Normal:
Systolic increases during exercise; returns to baseline by five to six minutes in recovery.
Hypotensive Response to Exercise: A drop in BP to baseline levels during exercise; poor prognosis.
Hypertensive Response to Exercise: Systolic greater than 220mmHg, or rise in diastolic of > 10mmHg, or
Stage II age predicted 95% DBP. Singh et al: BP response during treadmill testing as a risk factor for
new-onset hypertension. Circulation. 1999;99:1831-1836. Blood Pressure in Recovery:
3 Minute Systolic BP Ratio: SBP 3 min/ SBP Peak > 0.91 is abnormal. Taylor et al: Postexercise systolic BP response: clinical application
to the assessment of ischemic heart disease. American Family Physician. Vol 58(5).
Common Abnormal Responses to Exercise Stress Testing
ST Depression and Elevation Measurement:
Three Continuous beats Baseline is the junction of downsloping
PR and QRS complex Depression:
If ST elevated at rest c/w early repolarization, measure from baseline.
If ST depressed at rest, measure deviation from the baseline depression.
Elevation: ST elevation is c/w transmural
ischemia, however needs to be classified by whether it occurs over Q waves.
Over Q waves: ST elevation may occur in the presence of prior infarct, and may or may not represent ischemia.
Common Abnormal Responses Isolated Inferior Depression
Atrial repolarization has been demonstrated to cause J point depression in the inferior leads.
Isolated inferior lead ST depression is frequently a false positive.
ST Elevation ST segment elevation in the absence of Q
waves usually indicates transmural ischemia.
Exercise-Induced Bundle Branch Block Ischemia can be interpreted in RBBB, but
not LBBB. The Stress test should be stopped and the
patient should have further evaluation for structural heart disease.
Exercise-Induced Hypotension Always serious symptoms that warrant
further evaluation for structural heart disease.
Common Abnormal Responses Exercise-Induced Arrhythmias
Simple PVCs: not uncommon; low grade ectopy, unifocal, and infrequent PVCs during exercise do not increase risk.
Complex Arrhythmias: complex arrhythmias at low levels, in particular when associated with ischemia, warrant further evaluation.
Ventricular Tachycardia: require termination of the test, with prognosis based upon status of underlying heart disease.
Paroxysmal Atrial Tachycardia/PSVT: treated as patients who develop PSVT without exercise.
Determining Myocardial Ischemia Diagnostic of Myocardial
Ischemia Horizontal or downsloping ST
depression >1.0 mm at 60ms past the J point
ST elevation >1.0 mm at 60ms past the J point
Upsloping ST depression >1.5 at 80 ms past the J point
Negative for Myocardial Ischemia Patient has exercised to atleast
85% of maximal predicted heart rate and none of the above are present.
Suggestive of Myocardial Ischemia Horizontal or downsloping ST
depression 0.5 – 1.0 ST elevation 0.5 – 1.0 Upsloping ST depression >.7
<1.5 Exercise-induced hypotension Chest pain that seems like
angina High grade ventricular ectopy A new third heart sound
Inconclusive Patient does not achieve 85% of
maximum HR and has no ischemia.
The Final Report First Paragraph: (General Summary)
Pt’s age, indication for testing, cardiac medications and protocol. Baseline heart rate, BP and resting ECG findings. Peak exercise data, BP, HR, peak METs, RPE and reason for
stopping. Description of abnormalities in ECG response, hemodynamics,
dysrhythmias, or symptoms Second Paragraph: (Assessment)
Presence or absence of ischemia Normal or abnormal HR/BP response Presence of dysrhythmias Presence of symptoms Maximal aerobic capacity
Interpretation of the Exercise Stress Test
Bayes Theorem Theory of Conditional Probability
The predictive value of a test depends upon the descriptors of the test accuracy as well as the prevalence of disease in the population being tested.
Patients with an abnormal test and a low pre-test probability of disease are at risk for a false-positive.
Patients with a normal test and a high pre-test probability of disease are at risk for a false negative test.
The treadmill is thought to have a sensitivity of 70% and a specificity of 80% for diagnosing CAD.
Pre-Test and Post-Test Probability
Diamond and Forrester Curves
Common Errors False-Negative Tests
Failure to reach an adequate workload
Insufficient number of leads Single vessel disease Good collateral circulation Technical or observer error
False-Positive Tests Pre-existing abnormal ECG Cardiac hypertrophy WPW and other conduction
abnormalities Drugs Cardiomyopathy Hypokalemia Vasoregulatory abnormalities Mitral valve prolapse Pericardial disorders Pectus excavatum Coronary spasm Anemia Female gender Observer error
Predicting Severity of Disease Electrocardiographic Responses
ST depression > 2.5mm ST depression beginning at 5 METs or
less Downsloping ST depression or ST
elevation ST depression lasting more than 8
minutes into recovery Serious dysrhythmias at a low heart rate ST depression in more than 5 leads
Nonelectrocardiographic Response Chronotropic incompetence Exercise-induced hypotension Inability to exercise past 5 METs
Determining Prognosis Duke Treadmill Score
Exercise Treadmill Score = Minutes of Exercise – (5 x max ST depression) – (4 x Anginal Index)
Anginal Index: 0 – no angina; 1 typical; 2 – terminated test
secondary to angina. Scoring:
>5 – good prognosis with 5 yr survival of 97%
-10 to 4 – intermediate prognosis
-11 < - poor prognosis 5 yr survival of 72%
DUKE Treadmill Score for Stable CAD
METs - 5 X [mm Exercise-Induced ST Depression] - 4 X [Treadmill Angina Index]
Duke Treadmill Score Nomogram
But Can Physicians do as well as the Scores? 954 patients - clinical/ETT reports Sent to 44 expert cardiologists, 40
cardiologists and 30 internists Scores did better than all three but was
most similar to the experts
How to read an Exercise ECG Good skin prep PR isoelectric line Not one beat Three consistent complexes Averages can help Garbage in, garbage out Why watch during recovery?
Symptom-Sign Limited Testing Endpoints – When to stop! Dyspnea, fatigue, chest pain
Systolic blood pressure drop
ECG--ST changes, arrhythmias
Physician Assessment
Borg Scale (17 or greater)
Problems with Age-Predicted Maximal Heart Rate Which Regression Formula? (2YY - .Y x Age) Big scatter around the regression line
– poor correlation [-0.4 to -0.6] – One SD is plus/minus 12 bpm
A percent value target will be maximal for some and sub-max for others
Confounded by Beta Blockers Borg scale is better for evaluating Effort Target Heart Rate does have a place as an Indicator of
Effort or adequacy of test
Comparison of Tests for Diagnosis of CAD
Grouping # of Studies
Total # Patients
Sens Spec Predictive Accuracy
Standard ET 147 24,047 68% 77% 73% ET Scores 24 11,788 80% Score Strategy 2 >1000 85% 92% 88%
Thallium Scint 59 6,038 85% 85% 85% SPECT 16+14 5,272 88% 72% 80% Adenosine SPECT 10+4 2,137 89% 80% 85% Exercise ECHO 58 5,000 84% 75% 80% Dobutamine ECHO 5 <1000 88% 84% 86% Dobutamine Scint 20 1014 88% 74% 81% Electron Beam Tomography (EBCT)
16 3,683 60% 70% 65%
Function is Everything!