exercise treadmill testing prognostication in coronary artery disease dr. peter krampl 11 october...

Exercise Treadmill TestingExercise Treadmill Testing

Prognostication in Coronary Artery Disease

Dr. Peter Krampl

11 October 2001

IntroductionIntroduction

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

or negative diagnosis of coronary syndromes


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


Current ED Modalities– ECG

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


Current ED Modalities– Cardiac Markers– Hedges et al. Acad EM. (CK-MB)

1042 patients; CK-MB at presentation and serial investigated Sensitivity 19-31% Specificity 95-96%

– Hamm et al. NEJM. 1997 (TnT) 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%


Are We Satisfied With Those Numbers?How Do We Further Risk Stratify Coronary

Patients?– Treadmill Testing– Observation Units / Time– Radionuclear Imaging +/- Exercise– Echocardiography +/- Exercise– Angiography


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.

What do those mean?Can we use those simple guides to further

stratify these patients?

What Use Has The Exercise Stress Test?

OutlineOutline

Introduction Treadmill Testing

Review of Current Literature– Introduction– Indications– Procedures– Results– Notable Studies

Exercise Modalities Conclusions Questions

Treadmill Testing: IntroductionTreadmill Testing: Introduction

Froelicher. Hdbk of Exercise Testing. 1996

Goals– Diagnosis CAD– Prognosis CAD – Evaluation of Medical Therapy– Evaluation of Exercise Capacity

Treadmill Testing: IndicationsTreadmill Testing: Indications

When to use….– AHA / CPSA guidelines advise to use only up to

intermediate pre test probability cases– Kuntz et al. Ann Int Med. 1999.

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


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

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


Majority of tests done on referral basis Advent of chest pain units in United States…

– Studies by 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


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


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


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


Contraindications– AHA Guidelines– Absolute

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


Contraindications– Relative

High degree AV block Moderate stenotic valvular disease DBP >200 or DBP > 110 Bradyarrythmias Known left main coronary stenosis Mental / physical incapacity


Complications

– Brady / Tachyarrythmias

– AMI / Sudden Death

– CHF / Shock

– MSK Trauma / Fatigue / Malaise

Treadmill Testing: ProceduresTreadmill Testing: Procedures

Important Concepts– VO2 max : maximum oxygen uptake

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 wall tension, thickness, contractility and HR Estimated by double product (HR X BP) Angina usually occurs at the same double product


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

Age, sex, motivation, habitus, blood volume, health

– SBP increases with exercise– DBP stays same or slightly decreases– Hypotension ominous sign

Outflow obstruction, ventricular dysfunction or ischemia


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


Preparation– Fast 3 hours prior / dress appropriately… footwear– Medications reviewed by physician prior– History and physical prior regarding change in disease

CHF; valvular disease; onset of unstable angina; bronchospasm

– Consent– Baseline supine and upright ECG


Protocols– Most diagnostic and prognostic studies based on Bruce

protocol 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:ProceduresTreadmill Testing:Procedures

Borg Scale– Borg. Sports and Exercise. 1982.– Correlation of scale to actual fatigue– 6-20 grade scale for exertion– 10 grade scale for exertion now adopted

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


Measurements– 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


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


Termination– Relative

Maintenance of SBP well into protocol Excessive ST / QRS changes Fatigue, SOB, Wheeze, Cramps, Claudication SVT Development of BBB

– Observation Important !! Case 77 y.o. male; level one indications; no contraindications;

stable angina– Maintenance of SBP into Phase 2

Treadmill Testing: ResultsTreadmill Testing: Results

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.

Original Duke University Investigators showed repeated studies of poor specificity and positive predictive value


Diagnostic– Lehmann and Froelicher. Veteran’s Study

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%


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


Prognostic– Mark et al. Duke University. Ann Int Med 1987;– Validation Mark et al. NEJM. 1991.

– 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


Prognostic– Duke Score

Time in minutes ST depression in mm Type of pain

0 - none1 – typical anginal pain

limited by time / fatigue / other2 – limiting anginal pain


Duke Score =

Time(m) – 4X Angina – 5X depression(mm)

Score: 5 & above low risk

4 to –9 intermediate risk

-10 & below high risk


Kowk et al. JAMA. 1999. Revisited Duke Score2405 patients939 had ST segment changes on stress testFound 97 % seven year survival based on

score Duke > 5These studies have solidified the

prognostic benefits of the treadmill test


Duke score– Low Risk

Less than 1% per year acute coronary syndrome Optimize Medical Rx; reassess in one year

– Intermediate Risk 1 to 5 % per year Optimize Medical Rx; nuclear studies non-urgent

– High Risk Greater than 5 % per year Urgent referral for further risk stratification


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


Exercise Capacity– AHA Guidelines– Carliner et al. Am J Card. 1985– Reasonable to Use exercise testing for

Surgical patients recovering from – Congenital repair– Valvular replacement– Cardiac transplant

CHF DM CRF Chronic Lung Disease

– No exercise induced symptoms


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


AHA Guidelines Evaluation of Medical Therapy

– Look for improvement of exercise capacity to previous before angina or ST depression

Evaluation of Valvular Disease– Strict guideline for evaluation of AS

Evaluation of Dysrrythmias– PVC, Sick sinus Syndrome

Pre-operative– Anesthetists 2nd largest user of stress test for evaluation of

patient for non cardiac surgery

Notable StudiesNotable Studies

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


Variables– Prakash et al. Am Heart J. 2001– 3974 men– Kaplan-Meier regression– Four variables predict mortality within 5 year

Rate of change of rate-pressure product Age > 65 Maximum MET <5 LVH on ECG


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


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.


Women Large number of false positives

– Mitral valve prolapse;– Higher incidence atypical chest pain– Hormonal, esp. estrogen mimickery of digoxin– Ventilation Responses and Metabolic Alkalosis

Curzen. Heart. 1998.– 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


Early Stress Testing– Polanczyk. Am J Card. 1998.– 276 low risk patients– Stress test within 48 hours– Similar prognostication numbers

0.5 % event rate

– Additional variables over 6 months 15% less ED visits 30% fewer admission

Exercise ModalitiesExercise Modalities

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


Thallium 201– Older agent; Replaces potassium in cells– Advantages

Able to calculate lung heart ratios

– Disadvantages Immediate imaging Poor in obese patients and large breasted women

– Maddahi. Am J Coll Card. 1989 Increases sensitivity from 60-70% of treadmill test to 90%

overall with addition of perfusion studies but 70% with single vessel disease


Technetium-99m sestamibi– Deposited into mitochondria– Advantages

Longer half life Better images Improved estimates of ejection fraction

– Disadvantage Poor extraction from blood at high blood flow

– Hachamovitch et al. Circulation. 1996. 834 patients; treadmill, Tc-99m and catheterization 78% of the listed 0.6% mortality from Duke Low Treadmill

prognostication caught as severe perfusion scans.


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.”

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

ConclusionsConclusions

Prognosis– Appropriate population in step wise work-up

Common Sense– 55 y.o male; 6 minutes; no angina; no ST changes; no

change in systolic BP…. In helping to risk stratify patients after initial (ED)

work-up, do exercise treadmills meet our need?– Set indications & structure– Understand what the test does and doesn’t tell us– Calgary / Rural Centres / Emergency Departments– Ongoing Studies…

ResourcesResources

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)

ACC / AHA Cardiology Guidelines. 1995.– Updated with review 1997.

CPSA Guidelines. 2000.

exercise treadmill testing prognostication in coronary artery disease dr. peter krampl 11 october...

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