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ECG exercise tolerance testing (ETT)

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 a) exercise capacity b) blood pressure & heart rate response to exercise c) possibly, provoked symptoms Disadvantages: 1) not useful when baseline ECG is abnormal# 2) accuracy depends on pretest probability of disease 3) abnormalities predict increased risk, but with uncertain implications regarding treatment [6] 4) ischemia on exercise stress testing does not predict cardiovascular events or change in LV ejection fraction in patients with stable multivessel coronary artery disease [11] # see Contraindications Indications: 1) initial diagnostic study for coronary artery disease (CAD) in most patients* a) evaluation of chest pain (typical or atypical for angina) b) latent CAD 2) evaluation of severity & prognosis of CAD 3) evaluation of functional capacity 4) evaluation of therapy (medical &/or surgical) 5) evaluation of arrhythmia a) *arrhythmias that occur spontaneously with exercise - most arrhythmias are not exercise related [2] b) *peak heart rate in a patient with an implantable defibrillator c) *ventricular response in patients with atrial fibrillation d) *response of rate-responsive pacemaker during exercise 6) post MI predischarge evaluation 7) evaluation of hypoxemia or oxygen desaturation [3] * high sensitivity for left main, 3-vessel & severe 2-vessel coronary artery disease Contraindications: 1) absolute a) acute myocardial infarction (<10 days) b) uncontrolled, unstable angina c) decompensated congestive heart failure d) active myocarditis or pericarditis e) uncontrolled major arrhythmia 1] ventricular 2] supraventricular 3] heart block f) excessive hypertension (systolic BP > 200 mm Hg) g) marked postural hypotension (systolic BP drop > 20 mm Hg) h) critical aortic stenosis - severe aortic stenosis with worsening symptoms [9] i) other major acute illness 2) relative: (renders test uninterpretable) a) left ventricular hypertrophy (LVH) b) atrial fibrillation c) digoxin d) left bundle branch block (LBBB) e) mitral valve prolapse f) T-wave abnormalities g) ST segment abnormalities (> 0.5 mm ST segment depression) [2] h) paced rhythm i) WPW syndrome j) prior revascularization 3) routine screening of asymptomatic patients [6] Procedure: 1) Bruce protocol 2) Naughton protocol 3) Blake protocol 4) Ellestad protocol Discontinue beta-blocker 24-48 hours prior to testing [2] 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 1) fatigue or dyspnea on exertion 2) maximum heart rate 3) angina (3 out of 4) 4) progressive ST segment depression 5) arrhythmia a) ventricular tachycardia (a run of 3 or more PVCs) b) rapid supraventricular arrhythmia c) heart block 6) blood pressure (BP) abnormalities a) progressive drop in BP with increasing workload (> 20 mm Hg) b) anxious normal individuals may drop BP during stage I c) excessive elevation of systolic BP (> 250 mm Hg) 7) signs of hypoperfusion a) lightheadedness b) pale color c) clammy skin 8) intermittent claudication 9) musculoskeletal limitations or balance difficulties 10) other reasons Criteria for positive ECG response 1) normal resting ST segment a) > 1 mm ST segment depression in 2 contiguous ECG leads [2] b) 1 mm J point depression with horizontal or downsloping ST segment c) 1.5 mm ST depression at 80 msec after the J point with upsloping ST segment 2) abnormal resting ST segment - 2 mm of additional ST segment depression 3) patient on digitalis - same criteria as normal resting ST segment if patient achieves > 90% maximum predicted heart rate * 1 mm horizontal ST segment depression that resolves in the 1st minute of recovery does not meet criteria for further testing, but does suggest a component ischemic heart disease [9] - cardiac rehabilitation is recommended vs myocardial perfusion testing (pharmacologic testing) or cardiac catheterization Blood pressure: 1) normal response of systolic blood pressure to increasing workloads is 160-200 mm Hg - also see hypertensive response to exercise 2) in normal subjects, diastolic blood pressure does not change significantly 3) 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 a) myocardial ischemia b) cardiomyopathy c) cardiac arrhythmias d) vasovagal reactions e) left ventricular outflow obstruction f) ingestion of antihypertensive drugs g) hypovolemia h) prolonged vigorous exercise Other prognostic/diagnostic factors: 1) achievement of a high workload (good prognosis) 2) typical angina during exercise a) adds diagnostic & prognostic information b) occurring at < 6 METS (before the end of stage 2 of the Bruce protocol) is an indication for coronary angiography 3) persistence of ST segment depression into recovery 4) increased heart rate of > 12/min during 1st minute of exercise is associated with increased risk of myocardial infarction [3] 5) self-reported dyspnea is an independent risk factor for myocardial infarction [4] 6) high-grade premature ventricular contractions during the recovery period following exercise may be associated with increased cardiovascular risk [12] 6) higher incidence of false-positive ST segment depression in women* [2] 7) sensitivity is also lower in women* * recommendations are generally the same for men & women [2] Management: - a positive test warrants referral for myocardial perfusion test or cardiac catheterization - stress echocardiography if baseline ST segment abnormalities (> 0.5 mm ST segment depression) confound interpretation [2] - if the exercise stress test is inadequate, a pharmacologic stress test should be performed [2] - symptomatic patients with an abnormal test that does not meet criteria for a positive test may benefit from cardiac rehabilitation [9] - Duke treadmill score may provide useful risk information [2] Notes: - rapid resolution of ECG changes during exercise portends negative followup testing & good prognoses [7] - angina pectoris despite negative ECG findings portends positive followup testing & poorer prognosis - chest tightness & breathlessness in a man with history of myocardial infarction in the absence of ECG changes constitutes low risk [2] - younger age, female sex, & achieving a higher level of exercise portend negative followup testing [7]

Related

Duke treadmill score electrocardiogram (ECG, EKG) hypertensive response to exercise (HRE)

Specific

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

General

exercise stress testing

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, 16, 17, 18. American College of Physicians, Philadelphia 1998, 2006, 2009, 2012, 2015, 2018.
  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: 16172270
  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 http://www.utdol.com
  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 PMID: 21930855 http://www.annals.org/content/155/6/375.abstract - Lauer MS What Now With Screening Electrocardiography? Annals of Internal Medicine 2011, 155(6):395-397 PMID: 21930859 http://www.annals.org/content/155/6/395.extract - US Preventive Services Task Force Screening for Coronary Heart Disease Release Date: February 2004 http://www.uspreventiveservicestaskforce.org/uspstf/uspsacad.htm
  7. Christman MP et al. The yield of downstream tests after ETT: A prospective cohort study. J Am Coll Cardiol 2014 Feb 5 PMID: 24509269 http://www.sciencedirect.com/science/article/pii/S0735109714002897 - Sinusas AJ and Spatz ES. Reframing the interpretation and application of exercise electrocardiography. J Am Coll Cardiol 2014 Feb 5; PMID: 24509274 http://www.sciencedirect.com/science/article/pii/S0735109714002800
  8. Mark DB, Hlatky MA, Harrell FE Jr, Lee KL, Califf RM, Pryor DB Exercise treadmill score for predicting prognosis in coronary artery disease. Ann Intern Med. 1987 Jun;106(6):793-800 PMID: 3579066
  9. Geriatric Review Syllabus, 9th edition (GRS9) Medinal-Walpole A, Pacala JT, Porter JF (eds) American Geriatrics Society, 2016 - Geriatric Review Syllabus, 11th edition (GRS11) Harper GM, Lyons WL, Potter JF (eds) American Geriatrics Society, 2022
  10. Mieres JH, Gulati M, Bairey Merz N et al Role of noninvasive testing in the clinical evaluation of women with suspected ischemic heart disease: a consensus statement from the American Heart Association. Circulation. 2014 Jul 22;130(4):350-79. PMID: 25047587
  11. Garzillo CL, Hueb W, Gersh B et al. Association between stress testing-induced myocardial ischemia and clinical events in patients with multivessel coronary artery disease. JAMA Intern Med 2019 Jul 22 PMID: 31329221 Free PMC Article https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2738785
  12. Swift Yasgur B Post-Exercise PVCs Tied to Higher CV Mortality Risk. Medscape. Dec 2, 2021 https://www.medscape.com/viewarticle/964055