Diagnostic Testing for Suspected Angina

Initial Diagnostic Approach

The American College of Cardiology recommends exercise ECG testing using the Bruce protocol with Duke treadmill score as the initial diagnostic test for patients with suspected stable angina who can exercise, have a normal resting ECG, and are not taking digoxin 1, 2
The European Heart Journal suggests obtaining a 12-lead resting ECG in all patients with chest pain to identify baseline abnormalities and assess for acute ischemia 3
Resting transthoracic echocardiography is recommended to exclude alternative causes of angina, identify regional wall motion abnormalities, measure left ventricular ejection fraction for risk stratification, and evaluate diastolic function 3

The Duke treadmill score is calculated using the formula: Exercise time (minutes) − (5 × ST deviation in mm) − (4 if angina occurs) − (8 if angina causes test termination) 1, 2
The score categorizes patients into low-risk (score ≥5), moderate-risk (score −10 to +4), and high-risk (score ≤−10) groups, with corresponding 4-year survival rates of 99%, intermediate prognosis, and 79% 1, 2, 7

Stress imaging (nuclear perfusion or echocardiography) is recommended as the initial test in patients with baseline ECG abnormalities, unable to exercise, previous coronary revascularization, high pretest probability, or taking digoxin 1, 5, 6
For patients with low-risk unstable angina, wait a minimum of 8-12 hours after being free of active ischemic or heart failure symptoms before stress testing 7, 8
Intermediate-risk patients should wait 2-3 days after stabilization before testing, while high-risk patients should proceed directly to coronary angiography without stress testing 7, 8