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Exercise Treadmill Testing

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Exercise Treadmill Testing

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    1. Exercise Treadmill Testing Chris Place, MD December 2, 2004

    3. Basic EKG Review

    4. Simple Method of EKG Interpretation Rate Rhythm Axis Hypertrophy Infarction and Ischemia

    6. 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.

    7. Axis

    10. Infarction and Ischemia

    19. 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

    20. 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.

    21. 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.

    22. 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.

    24. The Modified Borg Scale

    25. 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

    26. 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

    27. 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.

    28. 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.

    29. 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.

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

    31. 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.

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

    33. 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

    42. 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.

    43. 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

    44. Comparison of Tests for Diagnosis of CAD

    45. Results Reporting

    46. Results Reporting – Page 2

    47. 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

    48. 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;

    49. 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

    50. 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

    51. Results Reporting – Page 3

    56. Review 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

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