Treadmill Stress Testing for the Primary Care Physician

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Treadmill Stress Testingfor the Primary Care
Physician

• Francis G. OConnor, MD, FACSM
• Primary Care Sports Medicine

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Objectives

• Review essential Exercise Test Terminology
• Describe the Performance of the Exercise Stress
  Test
• Discuss Interpretation of the Exercise Stress
  Test
• Discuss Special Considerations in Athletes
• Review Indications for would-be Athletes

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Boring?.....
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Exercise Test Terminology

• The Electrocardiogram
• VO2max
• METs
• Myocardial Oxygen Consumption

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The Electrocardiogram
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The Electrocardiographic Response
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What is VO2max?
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Maximal Oxygen Uptake (VO2max)

• Greatest amount of oxygen an individual utilizes
  with maximal exercise (ml O2 per kilogram per
  minute)
• Gold Standard for cardiorespiratory fitness
• Fick Equation
• VO2max (HRmax x SVmax) x (CaO2max - CvO2max)

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FICK EQUATION
VO2max (HRmax X SVmax) X (CaO2max - CvO2max)
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METS
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Metabolic Equivalents (METs)

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

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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
• lt 5METs Poor prognosis if lt 65
• limit immediate post MI
• cost of basic activities of daily living

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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 Ooh lah lah Aerobic athlete

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Myocardial (MO2)

• Accurate measurement requires cardiac
  catheterization
• Coronary Flow x Coronary a - VO2 difference
• Wall Tension (Pressure x Volume, Contractility,
  Stroke Work, HR)
• Systolic Blood Pressure x HR
• Angina and ST Depression usually occurs at
  same Double Product in an individual Direct
  relationship to VO2 is altered by beta-blockers,
  training,...

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Myocardial Oxygen Consumption

• Indirectly measured as the Double Product
• Double Product HR x systolic blood pressure
• A normal value is greater than 20,000 25,000

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Objectives

• Review essential Exercise Test Terminology
• Describe the Performance of the Exercise Stress
  Test
• Discuss Interpretation of the Exercise Stress
  Test
• Discuss Special Considerations in Athletes
• Review Indications for would-be Athletes

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Performance of the Exercise Stress Test

• Indications/Contraindications
• Running the Exercise Test
• Physician Responsibilities

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ACSMs Guidelines for Exercise Testing and
Prescription

• ACSM. Lippincott, Williams Wilkins
• 6th Edition 2000

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Indications for Exercise Testing

• Class I Conditions for which there is evidence
  and/or general agreement that a given procedure
  or treatment is useful and effective.
• Class II Conditions for which there is
  conflicting evidence and/or a divergence of
  opinion about the usefulness/efficacy of a
  procedure or treatment.
• II a weight of evidence is in favor of
  usefulness/efficacy.
• II b usefulness is less well established by the
  evidence.
• Class III Conditions for which there is evidence
  and/or general agreement that the
  procedure/treatment is not useful/effective and
  in some cases may be harmful.

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Class I Indications for Performing an Exercise
Test

• Diagnosis of CAD in adults with intermediate
  pretest probability of disease
• Assess functional capacity and prognosis of
  patients with
• Known CAD
• Recent uncomplicated myocardial infarction
• Evaluate symptoms of recurrent, exercise-induced
  arrhythmias

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Class II Indications for Performing an Exercise
Test

• To evaluate asymptomatic men gt40 and women gt50
  who
• are involved in special, high risk occupations
• plan to start a vigorous exercise program
• have multiple cardiac risk factors.
• To assist in the diagnosis of CAD in adult
  patients with a high or low pretest probability
  of disease.
• To evaluate patients with a Class I indication
  who have baseline electrocardiographic changes.

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Class III Indications for Performing an Exercise
Test

• Routine screening of asymptomatic men or women.
• To evaluate men or women with a history of chest
  discomfort not thought to be of cardiac origin.
• To evaluate patients with simple PVCs on a
  resting ECG with no other evidence of CAD.
• To assist in the diagnosis of CAD in patients
  with evidence of LBBB or WPW on a resting ECG.

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Pre Test Probability of Coronary Disease by
Symptoms, Gender and Age
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Contraindications to GXT Testing Absolute

• Recent acute MI
• Unstable angina
• Ventricular tachycardia
• Dissecting aortic aneurysm
• Acute CHF

• Severe aortic stenosis
• Active myocarditis
• Thrombophlebitis or intracardiac thrombi
• Recent pulmonary embolus
• Acute infection

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Contraindications to GXT Testing Relative

• Uncontrolled severe hypertension
• Moderate aortic stenosis
• Severe subaortic stenosis
• Supraventricular dysrhythmias
• Ventricular aneurysm

• Complex ventricular ectopy
• Cardiomyopathy
• Uncontrolled metabolic disease
• Recurrent infectious disease
• Complicated pregnancy

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So What Do You Do.

• 39 yo female with risk factors and a squirrelly
  story.

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Comparison of Tests for Diagnosis of CAD
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Which Protocol?

• Vast Majority (82) use BRUCE
• So, why not you?

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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?

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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)

MHR220-age...
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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

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METS
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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???

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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.

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• Following the GXT, 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.

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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

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Heart Rate Drop in Recovery

• Probably not more predictive than Duke Treadmill
  Score or METs
• Studies including censoring and CV mortality
  needed

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Objectives

• Review essential Exercise Test Terminology
• Describe the Performance of the Exercise Stress
  Test
• Discuss Interpretation of the Exercise Stress
  Test
• Discuss Special Considerations in Athletes
• Review Indications for would-be Athletes

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Interpretation of the Exercise Stress Test

• Must Contain Following Elements
• Exercise Capacity
• Hemodynamic
• Clinical
• Electrocardiographic
• Optional Other Stuff..

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Positive vs Suggestive

• ST Depression
• ? or ? 1mm at 60msec
• ? 1.5mm at 80msec
• ST Elevation
• 1mm at 60msec

• ST Depression
• ? or ? 0.5 - 1mm at 60msec
• ? 0.7 - 1.5mm at 80msec
• ST Elevation
• 0.5 1mm at 60msec

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Negative vs Inconclusive

• Above criteria not met and pt exercised to at
  least 85 MPHR

• Pt did not reach 85 MPHR, but no evidence of
  ischemia (B-Blocker??)

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DUKE Treadmill Score for Stable CAD

• METs - 5 X mm E-I ST Depression - 4 X
  Treadmill Angina Index
• Nomogram

E-I Exercise Induced
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Duke Treadmill Score (uneven lines, elderly?)
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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

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Objectives

• Review essential Exercise Test Terminology
• Describe the Performance of the Exercise Stress
  Test
• Discuss Interpretation of the Exercise Stress
  Test
• Discuss Special Considerations in Athletes
• Review Indications for would-be Athletes

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Special Considerations in Athletes

• Indications
• Athletic Heart Syndrome
• Test Interpretation

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Objectives

• Review essential Exercise Test Terminology
• Describe the Performance of the Exercise Stress
  Test
• Discuss Interpretation of the Exercise Stress
  Test
• Discuss Special Considerations in Athletes
• Review Indications for would-be Athletes

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Does the patient need a GXT?

• Controversial
• ACSM- Must be able to distinguish
• Moderate vs. vigorous exercise
• Apparently healthy vs. higher risk
• Older vs. younger

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ACSM Recommendations for Medical Examination and
Exercise Testing Prior to Participation
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ACSM Initial Risk Stratification by Age and
Cardiac Risk

• Moderate Risk
• Older individuals
• ? 2 risk factors

• Low Risk
• Men lt 45, Women lt55
• No cardiac symptoms
• ?1 risk factor

• Cardiac Risk Factors
• Cigarette smoking
• Fam Hx. of early CAD
• LDL gt130)
• Hypertension
• Impaired fasting gluc
• (gt110mg/dL)
• Obesity (BMI gt30)
• Sedentary lifestyle

Positive Risk Factor High serum HDL (gt60)
Positive Risk Factor
Positive Risk Factor
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ACSM Initial Risk Stratification by Age and
Cardiac Risk

• Low Risk
• Men lt 45, Women lt55
• No cardiac symptoms
• ?1 risk factor
• Moderate Risk
• Older individuals
• ? 2 risk factors
• High Risk
• Signs or Symptoms of cardiac dz
• Known cardiac, pulmonary or metabolic (DM)
  disease.

• Signs/Sx. CV Disease
• Chest pain or anginal equiv
• Dyspnea w/ mild exertion
• Dizziness or syncope
• Orthopnea/PND
• Ankle edema
• Palpitations or tachycardia
• Intermittent claudication
• Fatigue w/ normal activities

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Who Needs a GXT?

• Athlete with known CAD
• Anyone with symptoms of CAD
• Moderate risk patient for vigorous exercise
• Anyone with known medical disease

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Questions???
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