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Exercise Stress Test. Apiwan Nuttamonwarakul The 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.

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Exercise stress test

Exercise Stress Test

Apiwan Nuttamonwarakul

The Supreme Patriarch Center on Aging

Ministry of Public Health


Objectives

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 Test Essentials


Exercise stress testing and family physicians

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

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

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

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

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.

  • VO2max:

    • Fick Equation: VO2max = (HRmax x SV max) x (CaO2max – CvO2max)

    • Gold standard for aerobic fitness.


Metabolic equivalents mets

Metabolic Equivalents (METs)

  • 1 MET = 3.5 ml O2 per kilogram of body weight per minute


Key met values part 1

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

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 mo 2

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

Diffusion

Ventilation

Perfusion

(220 - Age)

Sinus Node Dysfunction

Drugs (e.g., B - blockers)

PaO2

Hgb [ ]

SaO2

  • Skeletal Muscles

    • Aerobic Enzymes

    • Fiber Type

    • Muscle Disease

  • Capillary Density

Genetic Factors (Heart Size)

Conditioning Factors Contractility/Afterload/Preload

Disease Factors

Wall Motion/Ventricular Fxn Valve Stenosis or Regurgitation

The Fick Equation

VO2max = (HRmax X SVmax) X (CaO2max - CvO2max)


Performance of the exercise stress test

Performance of the Exercise Stress Test


Equipment and protocols

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

Which Protocol?

  • Vast Majority (82+%) use BRUCE

  • So, why not you?


Treadmill protocols

Treadmill Protocols


Indications

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

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 cad

Pre-Test Probability of CAD


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


Acsm recommendations for exercise testing prior to exercise participation1

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 participation2

ACSM Recommendations for Exercise Testing Prior to Exercise Participation


Contraindications

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


Contraindications1

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

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

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

Performing the Test

  • Preparing the Patient

  • Monitoring the Patient

  • Terminating the Test

  • Recovery of the Patient


Preparing 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 patient1

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

Monitoring the Patient


Terminating the test

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

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 termination1

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

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

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

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

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

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

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

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

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

Common Abnormal Responses to Exercise Stress Testing


St depression and elevation

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

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 responses1

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.

Determining Myocardial Ischemia


The final report

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

Interpretation of the Exercise Stress Test


Bayes theorem

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

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

Common Errors


Predicting severity of disease

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

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

DUKE Treadmill Score for Stable CAD

METs - 5 X [mm Exercise-Induced ST Depression] - 4 X [Treadmill Angina Index]


Exercise stress test

Duke Treadmill Score Nomogram


But can physicians do as well as the scores

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

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

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)

MHR=220-age...


Problems with age predicted maximal heart rate

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

Comparison of Tests for Diagnosis of CAD


Function is everything

Function is Everything!


Exercise stress test

Thank you


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