Exercise Tolerance Testing

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Contents 1 More Specific Terms 2 Introduction 3 Indications 4 Contraindications 5 Procedure 6 More General Terms 7 Additional Terms 8 References

More Specific Terms

• Bruce protocol
• cardiopulmonary exercise testing
• Ellestad protocol
• Naughton protocol
• post-MI exercise testing; rehabilitation treadmill testing; predischarge exercise testing

Introduction

• Also referred to as a stress test, a diagnostic test in which the patient exercises on a treadmill, bicycle, or other equipment while heart activity is monitored by an ECG.
  

• Advantages

• provides data on

• exercise capacity
• blood pressure & heart rate response to exercise
• possibly, provoked symptoms
  

• Disadvantages

• not useful when baseline ECG is abnormal#
• accuracy depends on pretest probability of disease
• abnormalities predict increased risk, but with uncertain implications regarding treatment [6]
  

• # see Contraindications

Indications

• initial diagnostic study for coronary artery disease ( CAD) in most patients*

• evaluation of chest pain (typical or atypical for angina)
• latent CAD

• evaluation of severity & prognosis of CAD
• evaluation of functional capacity
• evaluation of therapy (medical &/or surgical)
• evaluation of arrhythmia

• arrhythmias that occur spontaneously with exercise
• peak heart rate in a patient with an implantable defibrillator
• ventricular response in patients with atrial fibrillation
• response of rate-responsive pacemaker during exercise

• post MI predischarge evaluation
• evaluation of hypoxemia or oxygen desaturation [3]

• * high sensitivity for left main, 3-vessel & severe 2-vessel coronary artery disease

Contraindications

• absolute

• acute myocardial infarction (<10 days)
• uncontrolled, unstable angina
• decompensated congestive heart failure
• active myocarditis or pericarditis
• uncontrolled major arrhythmia

• ventricular
• supraventricular
• heart block

• excessive hypertension ( systolic BP > 200 mm Hg)
• marked postural hypotension ( systolic BP drop > 20 mm Hg)
• critical aortic stenosis
• other major acute illness

• relative: (renders test uninterpretable)

• left ventricular hypertrophy ( LVH)
• atrial fibrillation
• digoxin
• left bundle branch block ( LBBB)
• mitral valve prolapse
• T-wave abnormalities
• paced rhythm
• WPW syndrome
• prior revascularization

• routine screening of asymptomatic patients [6]

Procedure

• Bruce protocol
• Naughton protocol
• Blake protocol
• Ellestad protocol
  

• The extremity electrodes are moved to the torso to reduce motion artifact. The arm electrodes are placed in the lateral aspect of the infraclavicular fossa & the leg electrodes are placed above the iliac crest & the rib cage. This results in a right axis shift & increased voltage in inferior leads. It may result in a loss of inferior Q waves &/or development of a new Q wave in aVL.
  
• Reasons for terminating a stress test

• fatigue or dyspnea on exertion
• maximum heart rate
• angina (3 out of 4)
• progressive ST segment depression
• arrhythmia

• ventricular tachycardia (a run of 3 or more PVCs)
• rapid supraventricular arrhythmia
• heart block

• blood pressure (BP) abnormalities

• progressive drop in BP with increasing workload (> 20 mm Hg)
• anxious normal individuals may drop BP during stage I
• excessive elevation of systolic BP (> 250 mm Hg)

• signs of hypoperfusion

• lightheadedness
• pale color
• clammy skin

• intermittent claudication
• musculoskeletal limitations or balance difficulties
• other reasons
  

• Criteria for positive ECG response

• normal resting ST segment

• 1 mm J point depression with horizontal or downsloping ST segment
• 1.5 mm ST depression at 80 msec after the J point with upsloping ST segment

• abnormal resting ST segment

• 2 mm of additional ST segment depression

• patient on digitalis

• same criteria as normal resting ST segment if patient achieves > 90% maximum predicted heart rate
  

• Blood pressure:

• normal response of systolic blood pressure to increasing workloads is 160-200 mm Hg

• also see hypertensive response to exercise

• in normal subjects, diastolic blood pressure does not change significantly
• failure to increase systolic blood pressure to > 120 mm Hg or sustained decreased in systolic blood pressure > 10 mm Hg below standing resting values is abnormal

• myocardial ischemia
• cardiomyopathy
• cardiac arrhythmias
• vasovagal reactions
• left ventricular outflow obstruction
• ingestion of antihypertensive drugs
• hypovolemia
• prolonged vigorous exercise
  

• Other prognostic/ diagnostic factors:

• achievement of a high workload (good prognosis)
• typical angina during exercise

• adds diagnostic & prognostic information
• occurring at < 6 METS (before the end of stage 2 of the Bruce protocol) is an indication for coronary angiography

• persistence of ST segment depression into recovery
• increased heart rate of > 12/min during 1st minute of exercise is associated with increased risk of myocardial infarction [3]
• self-reported dyspnea is an independent risk factor for myocardial infarction [4]
• higher incidence of false-positive ST segment depression in women [2]

More General Terms

• ECG stress testing

Additional Terms

• electrocardiogram (ECG, EKG)
• hypertensive response to exercise (HRE)

References

1. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 86
2. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, American College of Physicians, Philadelphia 1998, 2006, 2009
3. Falcone C, Buzzi MP, Klersy C, Schwartz PJ. Rapid heart rate increase at onset of exercise predicts adverse cardiac events in patients with coronary artery disease. Circulation. 2005 Sep 27;112(13):1959-64. Epub 2005 Sep 19. PMID: [1]
4. Abidov A et al. Prognostic significance of dyspnea in patients referred for cardiac stress testing. N Engl J Med 2005 Nov 3; 353:1889-98
5. UpToDate 14.1 [2]
6. Chou R et al Screening Asymptomatic Adults With Resting or Exercise Electrocardiography: A Review of the Evidence for the U.S. Preventive Services Task Force Annals of Internal Medicine 2011, 155(6):375-385 <PubMed> PMID: [3] <Internet> [4]
   - Lauer MS What Now With Screening Electrocardiography? Annals of Internal Medicine 2011, 155(6):395-397 <PubMed> PMID: [5] <Internet> [6]
   - US Preventive Services Task Force Screening for Coronary Heart Disease Release Date: February 2004 [7]
7. National Guideline Clearinghouse
   - Cardiac stress test supplement. Institute for Clinical Systems Improvement ngc-guideline: [8]
   - Exercise testing in asymptomatic adults: a statement for professionals From the American Heart Association Council on Clinical Cardiology, Subcommittee on Exercise, Cardiac Rehabilitation, and Prevention. ngc-guideline: [9]

exercise tolerance testing (ETT)