Exercise Treadmill

Exercise Treadmill Testing

Chris Place, MD

December 2, 2004

Overview

• Basic EKG Review• Introduction to Treadmill Test

– Indications and Safety – Equipment and Protocols – Exercise End Points – Basics of Interpretation of the Exercise Test

• Exercise Testing to Diagnose Obstructive Coronary Artery Disease – Rationale and Guidelines– Pretest Probability – ST-Segment Interpretation– Confounders of Stress ECG Interpretation

• Result Reporting

Basic EKG Review

Simple Method of EKG Interpretation

• Rate

• Rhythm

• Axis

• Hypertrophy

• Infarction and Ischemia

Rate

Rhythm

• Identify basic rhythm…– …then scan entire tracing for pauses,

premature beats, irregularity, and abnormal waves.

• Always:– Check for:

• P before each QRS.• QRS after each P.

Axis

Hypertrophy

Infarction and Ischemia

Normal EKG

Atrial Fibrillation with Rapid Ventricular Response

Inferior Acute MI and RBBB

Anterior Acute MI

Left Ventricular Hypertrophy

Ventricular Fibrillation

Overview





Indications and Safety

• Generally a safe procedure, but both myocardial infarction and death have been reported and can be expected to occur at a rate of up to 1 per 2500 tests.

• Good clinical judgment should therefore be used in deciding which patients should undergo exercise testing.

• Exercise testing should be supervised by an appropriately trained physician.

• The electrocardiogram (ECG), heart rate, and blood pressure should be monitored carefully and recorded during each stage of exercise and during ST-segment abnormalities and chest pain.

Equipment and Protocols

• Both treadmill and cycle ergometer devices are available for exercise testing.

• Much of the published data are based on the Bruce protocol, there are clear advantages to customizing the protocol to the individual patient to allow 6 to 12 minutes of exercise.

• Exercise capacity should be reported in estimated metabolic equivalents

(METs) of exercise.

Exercise Endpoints

• Commonly terminated when subjects reach an arbitrary percentage of predicted maximum heart rate.

• Other end points (summarized next slide) are strongly preferred.

• The use of rating of perceived exertion scales, such as the Borg scale is often helpful in assessment of patient fatigue.

The Modified Borg ScaleSCALE SEVERITY

0 No Breathlessness* At All

0.5 Very Very Slight (Just Noticeable)

1 Very Slight

2 Slight Breathlessness

3 Moderate

4 Somewhat Severe

5 Severe Breathlessness

6

7 Very Severe Breathlessness

8

9 Very Very Severe (Almost Maximum)

10 Maximum

Basics of Interpretation of the Exercise Treadmill Test

• Interpretation of the exercise test should include exercise capacity and clinical, hemodynamic, and electrocardiographic response.

• The occurrence of ischemic chest pain consistent with angina is important, particularly if it forces termination of the test.

• The most important electrocardiographic findings are ST depression and elevation.

• Positive exercise test result is greater than or equal to 1 mm of horizontal or downsloping ST-segment depression or elevation for at least 60 to 80 milliseconds (ms) after the end of the QRS complex

Overview





Rationale for Using ETT to Diagnose Obstructive CAD

• Most predictive clinical finding is a history of chest pain or discomfort.

• Myocardial ischemia is the most important cause of chest pain and is most commonly a consequence of underlying coronary disease.

• CAD that has not resulted in sufficient luminal occlusion to cause ischemia during stress can still lead to ischemic events through spasm, plaque rupture, and thrombosis, but most catastrophic events are associated with extensive atherosclerosis.

• These nonobstructive lesions explain some of the events that occur after a normal exercise test.

• Although the coronary angiogram has obvious limitations, angiographic lesions remain the clinical gold standard.

The ACC/AHA Guidelines for the Diagnostic Use of the Standard Exercise Test

Class I (Definitely appropriate) - Adult males or females (including RBBB or < 1mm resting ST depression) with an intermediate pre-test probability of coronary artery disease based on gender, age and symptoms (specific exceptions are noted under Class II and III below).

Class IIa (Probably appropriate) - Patients with vasospastic angina.

The ACC/AHA Guidelines for the Diagnostic Use of the Standard Exercise Test

• Class IIb (maybe appropriate)– Patients with a high pretest probability of

CAD by age, symptoms, and gender. – Patients with a low pretest probability of CAD

by age, symptoms, and gender. – Patients with less than 1 mm of baseline ST

depression and taking digoxin. – Patients with electrocardiographic criteria for

left ventricular hypertrophy (LVH) and less than 1 mm of baseline ST depression.

The ACC/AHA Guidelines for the Diagnostic Use of the Standard Exercise Test, cont’d

Class III (Not appropriate) - 1. To use the ST segment response in the diagnosis of coronary

artery disease in patients who demonstrate the following baseline ECG abnormalities:pre-excitation (WPW) syndrome;electronically paced ventricular rhythm; more than one millimeter of resting ST depression;LBBB

2. To use the ST segment response in the diagnosis of coronary artery disease in

MI patients

Pretest Probability

• Based on the patient's history (including age, gender, and chest pain characteristics), physical examination and initial testing, and the clinician's experience with this type of problem.

• Typical or definite angina makes the pretest probability of disease so high that the test result does not dramatically change the probability.

• Atypical or probable angina in a 50-year-old man or a 60-year-old woman is associated with approximately a 50% probability of CAD.

• Diagnostic testing is most valuable in this intermediate pretest probability category, because the test result has the largest potential effect on diagnostic outcome.

• Typical or definite angina can be defined as 1) substernal chest pain or discomfort that is 2) provoked by exertion or emotional stress and 3) relieved by rest and/or nitroglycerin.

Pre Test Probability of Coronary Disease by Symptoms, Gender and Age

Age Gender Typical/DefiniteAngina Pectoris

Atypical/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%

• Computer summaries can help find possible areas of ischemia – then review raw data carefully!

• Determine PQ junction, J point, ST80, and estimate slope

• Elevation• Depression

– Upsloping– Horizontal– Downsloping

ST Segment Interpretation

Magnified ischemic exercise-induced ECG pattern. Three consecutive complexes with a relatively stable baseline are selected. The PQ junction (1) and J point (2) are

determined; the ST 80 (3) is determined at 80 msec after the J point. In this example, average J point displacement is 0.2 mV (2 mm) and ST 80 is 0.24 mV (2.4 mm). The

average slope measurement from the J point to ST 80 is –1.1 mV/sec.

Normal

Rapid Upsloping

Minor ST Depression

Slow Upsloping

Horizontal

Downsloping

Elevation (non Q lead)

Elevation (Q wave lead)

J point depression of 2 to 3 mm in leads V4 to V6 with

rapid upsloping ST segments depressed

approximately 1 mm 80 msec after the J point. The ST segment slope in leads V4 and V5 is 3.0 mV/sec. This response should not be considered abnormal.

Upsloping

• In lead V4 , the exercise ECG result is abnormal early in the test, reaching 0.3 mV (3 mm) of horizontal ST segment depression at the end of exercise. • Consistent with a severe ischemic response.

•The J point at peak exertion is depressed 2.5 mm, the ST segment slope is 1.5 mV/sec, and the ST segment level at 80 msec after the J point is depressed 1.6 mm. •This “slow upsloping” ST segment at peak exercise indicates an ischemic pattern in patients with a high coronary disease prevalence pretest. •A typical ischemic pattern is seen at 3 minutes of the recovery phase when the ST segment is horizontal and 5 minutes after exertion when the ST segment is downsloping.

•Becomes abnormal at 9:30 minutes (horizontal arrow right) of a 12-minute exercise test and resolves in the immediate recovery phase. •This ECG pattern in which the ST segment becomes abnormal only at high exercise workloads and returns to baseline in the immediate recovery phase may indicate a false-positive result in an asymptomatic individual without atherosclerotic risk factors.

•A 48-year-old man with several atherosclerotic risk factors and a normal rest ECG result developed marked ST segment elevation (4 mm [arrows]) in leads V2 and V3 with lesser degrees of ST segment elevation in leads V1 and V4 and J point depression with upsloping ST segments in lead II, associated with angina. •This type of ECG pattern is usually associated with a full-thickness, reversible myocardial perfusion defect in the corresponding left ventricular myocardial segments and high-grade intraluminal narrowing at coronary angiography. Rarely, coronary vasospasm produces this result in the absence of significant intraluminal atherosclerotic narrowing.(

Confounders of Exercise Treadmill Test Interpretation• Digoxin

– Produces an abnormal ST-segment response to exercise. This abnormal ST depression occurs in 25% to 40% of healthy subjects studied and is directly related to age.

• Left Ventricular Hypertrophy– Decreased specificity of exercise testing, but sensitivity is unaffected. Therefore,

a standard exercise test may still be the first test, with referrals for additional tests only indicated in patients with an abnormal test result.

• Resting ST Depression– Resting ST-segment depression has been identified as a marker for adverse

cardiac events in patients with and without known CAD.• Left Bundle-Branch Block

– Exercise-induced ST depression usually occurs with left bundle-branch block and has no association with ischemia. Even up to 1 cm of ST depression can occur in healthy normal subjects. There is no level of ST-segment depression that confers diagnostic significance in left bundle-branch block.

• Right Bundle-Branch Block– The presence of right bundle-branch block does not appear to reduce the

sensitivity, specificity, or predictive value of the stress ECG for the diagnosis of ischemia.

• Beta Blocker Therapy– For routine exercise testing, it appears unnecessary for physicians to accept the

risk of stopping beta-blockers before testing when a patient exhibits possible symptoms of ischemia or has hypertension. However, exercise testing in patients taking beta-blockers may have reduced diagnostic or prognostic value because of inadequate heart rate response.

Overview





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 S trategy 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%

E lectron Beam Tomography (EBCT)

16 3,683 60% 70% 65%

Results ReportingHope Medical GroupExercise Treadmill TestResults Report – rev. 11/04

Patient Name: Date of Test:Chart Number:Reason for Test:________________________________________________________________________Digoxin? _______Beta blocker? ________Resting EKG interpretation:________________________________________________________________________________________________________________________________________________LVH? ___________LBBB? __________RBBB? ___________Resting ST Depression? _________Cardiac Risk Factors (circle)

Age Gender Diabetes HTN

Hypercholesterolemia Smoker Sedentary/Obese Total Number:

Estimate pretest probability – use table for reference (very low, low, intermediate, high, very high):_______________________________________________________________________Reason for test if pretest probability not intermediate:_______________________________________________________________________

Results Reporting – Page 21. Exercise Capacity

METS achieved: _______________Minutes exercised: _______________

2. Clinical response to exerciseChest pain during test? ___________Chest pain reason for stopping test? __________Perceived exertion scale (BORG scale reached – 6 to 20): _________Reason for stopping test:_____________

3. Electrocardiographic response to exerciseST elevation (yes/no) ? ____________ST depression (yes/no)? ____________(positive = 1 mm of horizontal or downsloping ST-segment depression or elevation for at least 60 to 80 milliseconds (ms) after the end of the QRS complex)What leads? ___________ST quality (upsloping, horizontal,

downsloping):_______________ST depression amount (mm): ___________Dysrhythmia? _____________Other:____________________________________________________

4. Hemodynamic response to exerciseSystolic BP response: ______________Diastolic BP response: ______________Maximum heart rate achieved: ________________2 minute heart rate recovery (should be at least 22 bpm by 2 minutes):

______________

What is a MET?

Metabolic Equivalent Term

1 MET = "Basal" aerobic oxygen consumption to stay alive = 3.5 ml O2 /Kg/min

Actually differs with thyroid status, post exercise, obesity, disease states

Key MET Values

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;

Key MET Values (part 2)

10 METs = As good a prognosis with medical therapy as CABG

13 METs = Excellent prognosis, regardless of other exercise responses

16 METs = Aerobic master athlete

20 METs = Aerobic athlete

Calculation of METs on the Treadmill

METs = Speed x [0.1 + (Grade x 1.8)] + 3.5 3.5

Calculated automatically by Device!

Note: Speed in meters/minute conversion = MPH x 26.8

Grade expressed as a fraction

5. Duke treadmill scores (see nomogram or use calculator):

5-year survival _______Average annual mortality __________

6. VA treadmill score: _________

7. Final conclusions and recommendation for follow-up:__________________________________________________________________________________________________________________________________________________________________________________________

Results Reporting – Page 3

Duke treadmill score = duration of exercise in minutes on the Bruce protocol- (minus) 5x maximal mm ST deviation- (minus) 4x treadmill angina index

Treadmill Angina Index:0 if no angina.1 if non-limiting angina.2 if limiting angina.

High Risk = treadmill score < -1079% 4-year survivalModerate Risk = treadmill score -10 to +495% 4-year survivalLow Risk = treadmill score >+599% 4-year survival

Duke Nomogram for 2 mm depression, non-limiting chest pain at 5 METS.

Variable Circle response

Sum

Maximal Heart Rate Less than 100 bpm = 30

100 to 129 bpm = 24

130 to 159 bpm =18

160 to 189 bpm =12

190 to 220 bpm =6

Exercise ST Depression

1-2mm =15

> 2mm =25

Age >55 yrs =20

40 to 55 yrs = 12

Angina History Definite/Typical = 5

Probable/atypical =3

Non-cardiac pain =1

Hypercholesterolemia?

Yes=5

Diabetes? Yes=5

Exercise test Occurred =3

induced Angina Reason for stopping =5

Total Score:

MalesChoose

only one per

group

<40=low prob

40-60= intermediate probability

>60=high probability

Positive=-5, Negative=5

Total Score

Reason for stopping =15induced Angina

Estrogen Status

Occurred =9Exercise test

Yes=10Diabetes?

Yes=10Smoking?

Non-cardiac pain =2

Probable/atypical =6

Definite/Typical = 10Angina History

50 to 65 yrs = 15

>65 yrs =25Age

> 2mm =10Depression

1-2mm =6Exercise ST

190 to 220 bpm =4

160 to 189 bpm =8

130 to 159 bpm =12

100 to 129 bpm = 16Rate

Less than 100 bpm = 20Maximal Heart

SumCircle responseVariable WomenChoose

only one per

group

<37=low prob

37-57= intermediate probability

>57=high probability

Review





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Exercise Treadmill