Exercise Treadmill Testing for Suspected Coronary Artery Disease

Indications and Contraindications

The European Society of Cardiology recommends an exercise treadmill test (ETT) as the initial diagnostic test for patients with suspected coronary artery disease who have an intermediate pre-test probability (15-65%), can exercise adequately, are not on anti-ischemic medications, and have a normal baseline ECG that allows accurate interpretation 1, 2, 3
The American Heart Association suggests that patients must be physically capable of achieving at least 85% of maximum predicted heart rate to obtain interpretable results 4
A normal baseline ECG is required, with no ST-segment abnormalities, left bundle branch block, paced rhythm, Wolff-Parkinson-White syndrome, left ventricular hypertrophy with strain, or >1 mm ST depression at rest, as recommended by the European Society of Cardiology 3

The Duke Treadmill Score stratifies risk using the formula: exercise time (minutes) - (5 × ST deviation in mm) - (4 × angina index), with scores ≥5 indicating low risk, -10 to +4 moderate risk, and ≤-11 high risk, according to the American College of Cardiology 6
Exercise capacity measured in METs is one of the strongest prognostic indicators, with <5 METs or <100% age-predicted METs indicating high risk, as stated by the American Heart Association 6
A decrease in systolic blood pressure >10 mmHg from rest to peak exercise indicates high risk, as reported by the European Society of Cardiology 6

Expected complication rates are 0-6 deaths or cardiac arrests per 10,000 tests and 2-10 myocardial infarctions per 10,000 tests, according to the American Heart Association 4
The supervising physician must be trained in advanced cardiopulmonary resuscitation, with a defibrillator and emergency medications immediately available, as recommended by the American College of Cardiology 4

Low-risk Duke Treadmill scores (≥5) indicate excellent prognosis and generally do not require further imaging studies, according to the American College of Cardiology 8
Intermediate or high-risk scores warrant consideration of stress imaging or invasive coronary angiography depending on symptom severity and clinical context, as stated by the American Heart Association 8