Exercise ECG: technique, interpretation and contraindications
THE CONTEXT
Exercise electrocardiography records cardiac electrical activity during exertion to assess symptoms and inform the diagnosis of angina due to coronary artery disease.
Technique
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A 12-lead ECG is recorded during treadmill or bicycle exercise. Limb electrodes are placed on the shoulders and hips rather than the wrists and ankles.
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The Bruce Protocol is the most commonly used protocol. Blood pressure is recorded and symptoms are assessed during testing.
Positive test and diagnostic limitations
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The test is positive if angina occurs, blood pressure falls or fails to increase, or ST-segment shifts exceed 1 mm.
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Exercise testing objectively assesses symptom severity and informs the potential diagnosis of coronary artery disease-related angina, with reasonable sensitivity and excellent specificity in this setting.
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False-negative results occur in patients with coronary artery disease, and a positive result does not invariably indicate coronary artery disease.
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In low-risk individuals, including asymptomatic young or middle-aged women, an abnormal response is more likely to be false-positive than true-positive.
Contraindications
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Stress testing is contraindicated in acute coronary syndrome, decompensated heart failure and severe hypertension.