Transcript Prognostication in Coronary Artery Disease

Exercise Treadmill Testing
Prognostication in Coronary
Artery Disease
Dr. Peter Krampl
11 October 2001
Introduction
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300,000 ER visits per year acute non traumatic
chest pain
 Only apx. 25% have clear positive,
– Unstable coronary disease
Angiography
 Image studies
– Acute myocardial infarction
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or negative diagnosis of coronary syndromes
Introduction
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Current ED Modalities
– Reviewed in EM Clinics February 2001
– History / Physical
 Mair. Chest. 1995.
 110 patients; non traumatic chest pain
 Using NPV as most used indicator for admission
 PPV 53% NPV 75% for acute cardiac ischemia
Introduction
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Current ED Modalities
– ECG
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Rovan, American Journal Cardiology. 1989.
Multicentre Chest Pain Trial
Sensitivity 61% Specificity 90% for ischemia
– Current ST, Q, LBBB criteria
Variable Specific
– Addition of T wave abnormality
– Sensitivity increases to 95%
– Specificity may decreases to 23%
– Current computer algorithms tend to higher sensitivity
Introduction
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Current ED Modalities
– Cardiac Markers
– Hedges et al. Acad EM. (CK-MB)
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1042 patients; CK-MB at presentation and serial investigated
Sensitivity 19-31%
Specificity 95-96%
– Hamm et al. NEJM. 1997 (TnT)
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776 patients
Prospective study looking at prognosis of TnT and TnI and 30
day cardiac event rate
Negative values of T and I gave annual event rates of 1.1 and
0.3% respectively
Sensitivity 31%
Specificity 98%
Introduction
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Are We Satisfied With Those Numbers?
 How Do We Further Risk Stratify Coronary
Patients?
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Treadmill Testing
Observation Units / Time
Radionuclear Imaging +/- Exercise
Echocardiography +/- Exercise
Angiography
Introduction
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In ED, old chart or patient notes:
– I was on treadmill for 8 minutes.
– A negative treadmill.
– I did not have pain on the treadmill.
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What do those mean?
 Can we use those simple guides to further
stratify these patients?
 What
Use Has The Exercise
Stress Test?
Outline
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Introduction
 Treadmill Testing
 Review of Current Literature
– Introduction
– Indications
– Procedures
– Results
– Notable Studies
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Exercise Modalities
 Conclusions
 Questions
Treadmill Testing: Introduction
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Froelicher. Hdbk of Exercise Testing. 1996
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Goals
– Diagnosis CAD
– Prognosis CAD
– Evaluation of Medical Therapy
– Evaluation of Exercise Capacity
Treadmill Testing: Indications
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When to use….
– AHA / CPSA guidelines advise to use only up to
intermediate pre test probability cases
– Kuntz et al. Ann Int Med. 1999.
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Exercise stress test or rest echo most cost effective (mild-mod)
– Life expectancy
– Cost
– Incremental Cost Effectiveness over other modalities
For high risk, immediate coronary angio most cost beneficial.
Other stress modalities supplement to Exercise Treadmill
Treadmill Testing: Indications
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Braunwald et al. High / Intermediate / Low Risk /
Pretest Probability Guidelines published by AHA
1995. Reviewed by Primary Care Clinics. 2001
 Example: Low Risk
– Chest pain by history classified as “probable not or
definitely not angina
– normal ECG
– New onset angina 2 months
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No change in previous 2 months
– T wave flattening or inversion <1 mm in leads with
dominant R waves
– One risk factor other than diabetes
Treadmill Testing: Indications
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Majority of tests done on referral basis
 Advent of chest pain units in United States…
– Studies by
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Zalenski. Ann EM. 1997. Low and Intermediate Risk.
– Safety at 4-12 hours
Mikhail. Ann EM. 1997. Intermediate risk.
– Safety at 12 to 24 hours
Lewis. Am J Card. 1994. Low risk.
– Safety at 1-2 hours
Kirk. Ann EM. 1998. Low risk.
– Safety at 1-2 hours
– CP Observation Units have adopted 6 hours as Industry
standard for exercise port work up and stabilization
Treadmill Testing: Indications
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Indications
– Froelicher / Annals of EM
– Clear (Class 1)
 Evaluation of male patients with atypical symptoms
 Functional capacity testing
 Evaluation of exercise related dizziness, syncope,
palpitations
 Evaluation of Recurrent exercise induced
Arrhythmias
Treadmill Testing: Indications
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Indications
– Probable Benefit (Class 2)
 Evaluation of Women with atypical symptoms
 Evaluation of Variant Angina
 All those in Class one with baseline ECG changes
other than LBBB
 Evaluation of patients on digitalis or RBBB
Treadmill Testing: Indications
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Indications
– Not Indicated (Class 3)
 Assymptomatic young men / women with no risk
factors and high suspicion non cardiac chest
discomfort
 Evaluation of patients with LBBB
 Evaluation of Patients with Pre-excitation
Syndromes
Treadmill Testing: Indications
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Contraindications
– AHA Guidelines
– Absolute
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AMI within 3-5 days
Unstable angina not stabilized by medical therapy
Aortic dissection
Endo, Myo, or pericarditis
PE
Lower Extremity Thrombosis
Uncontrolled symptomatic cardiac arrhythmias
Severe aortic stenosis
Symptomatic severe and terminal heart failure
Treadmill Testing: Indications
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Contraindications
– Relative
 High degree AV block
 Moderate stenotic valvular disease
 DBP >200 or DBP > 110
 Bradyarrythmias
 Known left main coronary stenosis
 Mental / physical incapacity
Treadmill Testing: Indications
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Complications
– Brady / Tachyarrythmias
– AMI / Sudden Death
– CHF / Shock
– MSK Trauma / Fatigue / Malaise
Treadmill Testing: Procedures
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Important Concepts
– VO2 max : maximum oxygen uptake
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Amt of O2 transported for cellular metabolism
Useful to express in multiples of METS
CO X (arteriovenous oxygen difference)
METS used to standardize protocols
– MO2 : myocardial O2 uptake
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wall tension, thickness, contractility and HR
Estimated by double product (HR X BP)
Angina usually occurs at the same double product
Treadmill Testing: Procedures
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Physiology
– Exercise creates increase CO
– Four to six fold increase from rest at peak
– CO increase by increase HR and PB and decreased
vagal tone
– HR affected by
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Age, sex, motivation, habitus, blood volume, health
– SBP increases with exercise
– DBP stays same or slightly decreases
– Hypotension ominous sign
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Outflow obstruction, ventricular dysfunction or ischemia
Treadmill Testing: Procedures
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Equipment
– Treadmill or cycle ergometer
 Cycle has major pitfall of rapid fatigue of
quadriceps in older patients
 Most studies use treadmill
– Handrails, Rest Area
– Assistant, Supervisor
– Resuscitation Equipment
Treadmill Testing: Procedures
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Preparation
– Fast 3 hours prior / dress appropriately… footwear
– Medications reviewed by physician prior
– History and physical prior regarding change in disease
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CHF; valvular disease; onset of unstable angina; bronchospasm
– Consent
– Baseline supine and upright ECG
Treadmill Testing: Procedures
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Protocols
– Most diagnostic and prognostic studies based on Bruce
protocol
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Seven phases
Change in grade and speed every 3 minutes
Correlation with METS
Large incremental stages
Not correlated for height / weight / stride
– Ideal protocol lasts 6-12 minutes and adjusts for
patients ability
– Others include Naughton, McHenry, USAF, Blake
Treadmill Testing:Procedures
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Borg Scale
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Borg. Sports and Exercise. 1982.
Correlation of scale to actual fatigue
6-20 grade scale for exertion
10 grade scale for exertion now adopted
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0 – nothing
9 – very strong
10 – very, very strong
– Continues to be a clinical assessment of fatigue by
technician (skilled) and supervisor
– Mainly used as repetitive assessment tool in rehab
Treadmill Testing: Procedures
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Measurements
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ST depression / elevation (60-80 ms; J point changes)
ST slope (downsloping worse than horizontal)
Duration of changes into recovery
Exercise induced arrhythmias
Peak HR / BP
Total Duration
Exertional hypotension
Angina
Other exercise induced symptoms
Treadmill Testing: Procedures
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Termination
– Absolute
 Drop of SPB > 10
 Anginal Pain (other than non-limiting / known pain)
 CNS symptoms
 Signs of poor perfusion
 Serious Arrhythmias (runs of VT > 3; multiform)
 Technical Difficulties in monitoring
 Subject Request
Treadmill Testing: Procedures
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Termination
– Relative
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Maintenance of SBP well into protocol
Excessive ST / QRS changes
Fatigue, SOB, Wheeze, Cramps, Claudication
SVT
Development of BBB
– Observation Important !!
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Case 77 y.o. male; level one indications; no contraindications;
stable angina
– Maintenance of SBP into Phase 2
Treadmill Testing: Results
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Diagnostic
– Exercise Treadmill (ST response only)
Sens 66%
Spec 84%
Froelicher et al. Exercise. 1993.
Sens 70%
Spec 75%
Gianrossi. Meta-analysis. Circulation. 1989.
Using Bayes rules of pretest probability, these numbers
may only be applied to intermediate cases at best.
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Original Duke University Investigators showed repeated
studies of poor specificity and positive predictive value
Treadmill Testing: Results
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Diagnostic
– Lehmann and Froelicher. Veteran’s Study
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Group. QUEXTA. Ann Int Med. 1998.
814 patients
400 selected for decreased work-up bias
Only 40% Stress test ‘positive’ ST changes
correlated to > minimal luminal CAD
Overall sensitivity 45% specificity 85%
Treadmill Testing: Results
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Prognostic
– Giagnoni. NEJM. 1983
– Prospective following of 135 men with ST
changes vs. 379 controls
– Angina, MI, sudden death endpoints
– 5.55 percent risk increase
– Suggested that ECG positive ST changes
should be independent coronary risk factor
Treadmill Testing: Results
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Prognostic
– Mark et al. Duke University. Ann Int Med 1987;
– Validation Mark et al. NEJM. 1991.
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Developed score based on 613 patients (1983-85)
Validated on further 1420 patients
Simple score to prognosticate patients
Associated score > 5 with annual mortality of
– 0.25 % outpatients
– 0.6 %
inpatients
Treadmill Testing: Results
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Prognostic
– Duke Score
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Time in minutes
ST depression in mm
Type of pain
0 - none
1 – typical anginal pain
limited by time / fatigue / other
2 – limiting anginal pain
Treadmill Testing: Results
Duke Score =
Time(m) – 4X Angina – 5X depression(mm)
Score:
5 & above
4 to –9
-10 & below
low risk
intermediate risk
high risk
Treadmill Testing: Results
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Kowk et al. JAMA. 1999.
 Revisited Duke Score
 2405 patients
 939 had ST segment changes on stress test
 Found 97 % seven year survival based on
score Duke > 5
 These studies have solidified the prognostic
benefits of the treadmill test
Treadmill Testing: Results
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Duke score
– Low Risk
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Less than 1% per year acute coronary syndrome
Optimize Medical Rx; reassess in one year
– Intermediate Risk
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1 to 5 % per year
Optimize Medical Rx; nuclear studies non-urgent
– High Risk
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Greater than 5 % per year
Urgent referral for further risk stratification
Treadmill Testing: Results
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Other prognostic indices:
– Morrow & Froelicher. Ann IM. 1993.
– Veteran’s Score
 Exercise duration
 ST depression
 Rate of change of systolic BP during exercise
 History of CHF, digoxin use
– Low risk groups stratified with 2% annual
mortality
Treadmill Testing: Results
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Exercise Capacity
– AHA Guidelines
– Carliner et al. Am J Card. 1985
– Reasonable to Use exercise testing for
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Surgical patients recovering from
– Congenital repair
– Valvular replacement
– Cardiac transplant
CHF
DM
CRF
Chronic Lung Disease
– No exercise induced symptoms
Treadmill Testing: Results
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Exercise Capacity and Prognostication
– Lauer and Fletcher. Circulation. 1996.
– 1575 men; mean age 43
– Failure to achieve 85 % of age predicted
maximum heart rate
– associated with increase in death of 1.84
– Extrapolation techniques used
Treadmill Testing: Results
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AHA Guidelines
 Evaluation of Medical Therapy
– Look for improvement of exercise capacity to previous
before angina or ST depression
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Evaluation of Valvular Disease
– Strict guideline for evaluation of AS
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Evaluation of Dysrrythmias
– PVC, Sick sinus Syndrome
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Pre-operative
– Anesthetists 2nd largest user of stress test for evaluation
of patient for non cardiac surgery
Notable Studies
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Exercise Hypotension
– Dubach et al. Circulation. 1989
– Looking at SBP drop with exercise
– Looked at 0, 10, 20 drop of SBP
– Drop of 20 associated with increased PPV of at
least 50% Left Main or Triple Vessel Disease
Notable Studies
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Variables
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Prakash et al. Am Heart J. 2001
3974 men
Kaplan-Meier regression
Four variables predict mortality within 5 year
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Rate of change of rate-pressure product
Age > 65
Maximum MET <5
LVH on ECG
Notable Studies
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METS
– Ramamurthy et al. Chest. 1999.
– Found that sensitivity increases if MET >7
– Also found that METS achieved may be a
stronger variable than rate-pressure product
– High heart rate at low MET (<5) level carries
adverse prognosis
Notable Studies
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Risk Factors
– Am J Cardiol. MRFIT. 1985.
– Multiple Risk Factor Intervention Trial
– 12,866 participants
– Those with ST changes on Stress Treadmill
benefit to greater degree with risk factor
modification than controls.
Notable Studies
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Women
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Large number of false positives
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Mitral valve prolapse;
Higher incidence atypical chest pain
Hormonal, esp. estrogen mimickery of digoxin
Ventilation Responses and Metabolic Alkalosis
Curzen. Heart. 1998.
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205 women
Compared with coronary angiography
42 false positives & 31 false negatives (36 % of total)
Increase false positives correlated with
• Increasing age to 52
• Increasing coronary risks to 3
Notable Studies
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Early Stress Testing
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Polanczyk. Am J Card. 1998.
276 low risk patients
Stress test within 48 hours
Similar prognostication numbers
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0.5 % event rate
– Additional variables over 6 months
 15% less ED visits
 30% fewer admission
Exercise Modalities
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Stress Echocardiography
– Evaluate rest / stress changes in wall motion.
– Dobutamine given to stimulate beta-1
– Advantages: Readily available; little
equipment; transportable
– Disadvantages: poor images in up to 10%; user
dependant; hard in presence of previous
abnormalities
Exercise Modalities
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Thallium 201
– Older agent; Replaces potassium in cells
– Advantages
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Able to calculate lung heart ratios
– Disadvantages
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Immediate imaging
Poor in obese patients and large breasted women
– Maddahi. Am J Coll Card. 1989
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Increases sensitivity from 60-70% of treadmill test to 90%
overall with addition of perfusion studies but 70% with single
vessel disease
Exercise Modalities
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Technetium-99m sestamibi
– Deposited into mitochondria
– Advantages
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Longer half life
Better images
Improved estimates of ejection fraction
– Disadvantage
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Poor extraction from blood at high blood flow
– Hachamovitch et al. Circulation. 1996.
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834 patients; treadmill, Tc-99m and catheterization
78% of the listed 0.6% mortality from Duke Low Treadmill
prognostication caught as severe perfusion scans.
Exercise Modalities
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Two schools of thought:
– EM Clinics Feb 2001
– “as useful as exercise testing is, it has the limitations of
suboptimal sensitivity and specificity…. Imaging is a
necessity, not an optional component of stress testing”
vs. “exercise testing alone is a useful first step.”
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Froelicher. Primary Care. 2001.
– Quotes George Bernard Shaw “the doctor does the test
he is paid the most for” to stress our need for continued
evaluation of present modalities
Conclusions
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Prognosis
– Appropriate population in step wise work-up
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Common Sense
– 55 y.o male; 6 minutes; no angina; no ST changes; no
change in systolic BP….
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In helping to risk stratify patients after initial (ED)
work-up, do exercise treadmills meet our need?
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Set indications & structure
Understand what the test does and doesn’t tell us
Calgary / Rural Centres / Emergency Departments
Ongoing Studies…
Resources
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Staff, Division of Nuclear Medicine, FMC
 Dr. Stone, C-Plus Clinic
 Froelicher. Handbook of Exercise Testing. 1996.
 Reviews (individual studies plus)
– Primary Care Clinics. 2001.
– EM Clinics. 1998, 2001.
– Froelicher et al. Chest. 1999 (Pitfalls)
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ACC / AHA Cardiology Guidelines. 1995.
– Updated with review 1997.
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CPSA Guidelines. 2000.