Chronic stable angina exercise electrocardiography

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [mailto:mgibson@perfuse.org] Phone:617-632-7753; Associate Editor(s)-In-Chief: ; Smita Kohli, M.D.; Lakshmi Gopalakrishnan, M.B.B.S.

Overview
In patients with chronic stable angina, exercise ECG is more sensitive and specific to identify inducible ischemia and to diagnose coronary artery disease. ECG abnormalities associated with MI include: down sloping of ST-segment depression or elevation, accompanying angina that occurs at a low workload during early stages of exercise and persistent for more than 3-minutes after exercise. The reliability of diagnosis is shown to improve with the evaluation of ST changes in relation to heart rate. Bruce protocol or treadmill (expressed in terms of METs) or bicycle ergometer (expressed in terms of watts) are used to detect MI. Exercise ECG test must be terminated on the achievement of maximal predicted heart rate and/or if the patient becomes symptomatic or develops pain with significant ST-segment changes. Exercise ECG test also provides prognostic stratification to evaluate the response to medical therapy or revascularization.

Indications
An exercise ECG is more useful than the resting ECG in detecting myocardial ischemia and evaluating the cause of chest pain.

Diagnostic criteria
ST-segment changes suggestive of coronary artery disease include:
 * Down sloping or horizontal ST segment depressions are highly suggestive of myocardial ischemia, particularly when:
 * It occurs at a low workload,
 * It occurs during early stages of exercise,
 * It persists for more than 3 minutes after exercise, or
 * It is accompanied by chest discomfort that is compatible with angina.


 * In converse, up-sloping ST segments are much less specific indicators of coronary artery disease.

Sensitivity and Specificity

 * Exercise electrocardiography has a sensitivity of approximately 70% for detecting coronary artery disease.
 * Exercise electrocardiography has a specificity of approximately 75% for excluding coronary artery disease.
 * To assess the probability of coronary artery disease in an individual patient, the exercise ECG result must be integrated with the clinical presentation.


 * Conditions that increase the probability of exercise ECG yielding false positive results are:
 * An abnormal resting ECG associated with left ventricular hypertrophy, intraventricular conduction abnormalities, pre-excitation syndromes (Long Ganong Lewine Syndrome = LGL, Wolf-Parkinson-White syndrome = WPW and Mahaim type), electrolyte imbalance or therapy with digitalis
 * In women, the lower prior probability of CAD is associated with more false positive results on ECG.


 * On the other hand, a fall in systolic pressure of 10 mmHg or more during exercise or the appearance of a murmur of mitral regurgitation during exercise increases the probability that, an abnormal stress ECG is a true positive test result.

Treadmill exercise test

 * Treadmill exercise test is more preferable to bicycle exercise test (or ergometer) for detecting myocardial ischemia.


 * In patients who cannot perform treadmill exercise, pharmacologic stress scintigraphy or echocardiography is preferable to upper body arm exercise.


 * Variables of the Treadmill Exercise Test which indicate the high risk are:
 * Short exercise duration less than 5 METs,
 * Significant ST segment depression (magnitude ≥2 mm, starts at exercise stage I or II, duration of exercise test is <5 minutes and ≥5 leads with ST changes,
 * Significant changes in blood pressure: low peak systolic blood pressure (<130 mm Hg), significant decrease in systolic blood pressure during the test (below the resting standing blood pressure),
 * Inability to attain to the target heart rate,
 * Presence of exercise induced angina,
 * Presence of frequent ventricular ectopy (e.g. couplets or tachycardia) at low workload.



==ACC / AHA Guidelines- Exercise ECG for Diagnosis (DO NOT EDIT) == {{cquote|

Class I
1. Patients with an intermediate pretest probability of CAD based on age, gender, and symptoms, including those with complete right bundle-branch block or less than 1 mm of rest ST depression (exceptions are listed below in classes II and III). (Level of Evidence: B)

Class IIa
1. Patients with suspected vasospastic angina. (Level of Evidence: C)

Class IIb
1. Patients with a high pretest probability of CAD by age, gender, and symptoms. (Level of Evidence: B)

2. Patients with a low pretest probability of CAD by age, gender, and symptoms. (Level of Evidence: B)

3. Patients taking digoxin with ECG baseline ST segment depression less than 1 mm. (Level of Evidence: B)

4. Patients with ECG criteria for LV hypertrophy and less than 1 mm of baseline ST segment depression. (Level of Evidence: B)

Class III
1. Patients with the following baseline ECG abnormalities:
 * a. Preexcitation (Wolff-Parkinson-White syndrome). (Level of Evidence: B)
 * b. Electronically paced ventricular rhythm. (Level of Evidence: B)
 * c. More than 1 mm of rest ST depression. (Level of Evidence: B)
 * d. Complete left bundle-branch block. (Level of Evidence: B)

2. Patients with an established diagnosis of CAD due to prior MI or coronary angiography; however, testing can assess functional capacity and prognosis. (Level of Evidence: B)}}

==ESC Guidelines- Exercise ECG for Initial diagnostic assessment of angina (DO NOT EDIT) == {{cquote|

Class I
1. Patients with symptoms of angina and intermediate pre-test probability of coronary artery disease based on age, gender, and symptoms, unless unable to exercise or displays ECG changes which make ECG non-evaluable. (Level of Evidence: B)

Class IIb
1. Patients with more than 1 mm ST-depression on resting ECG or taking digoxin. (Level of Evidence: B)

2. In patients with low pre-test probability (less than 10% probability) of coronary disease based on age, gender, and symptoms. (Level of Evidence: B)}}

==ESC Guidelines- Exercise ECG for Routine re-assessment in patients with chronic stable angina (DO NOT EDIT) == {{cquote|

Class IIb
1. Routine periodic exercise ECG in the absence of clinical change. (Level of Evidence: C)}}

Related Chapter

 * Exercise EKG

Vote on and Suggest Revisions to the Current Guidelines

 * The Chronic Stable Angina Living Guidelines: Vote on current recommendations and suggest revisions to the guidelines

Guideline Resources

 * The ACC/AHA/ACP–ASIM Guidelines for the Management of Patients With Chronic Stable Angina


 * Guidelines on the management of stable angina pectoris: The Task Force on the Management of Stable Angina Pectoris of the European Society of Cardiology


 * TheACC/AHA 2002 Guideline Update for the Management of Patients With Chronic Stable Angina


 * The 2007 Chronic Angina Focused Update of the ACC/AHA 2002 Guidelines for the Management of Patients With Chronic Stable Angina