What is the appropriate work‑up for an abnormal treadmill exercise electrocardiogram?

Workup for Abnormal Treadmill EKG

Patients with abnormal treadmill exercise ECG findings should proceed to stress imaging (exercise echocardiography or myocardial perfusion imaging) rather than direct coronary angiography, unless high-risk features are present that warrant immediate invasive evaluation. 1

Risk Stratification Using Duke Treadmill Score

The Duke Treadmill Score is the critical first step in determining the urgency and type of subsequent testing: 1

• High-risk score (≤-11): Marked ischemia at low workload indicates need for stress imaging with consideration for direct coronary angiography if limiting symptoms present 1, 2
• Intermediate-risk score (-10 to +4): Proceed to exercise myocardial perfusion imaging or exercise echocardiography 2
• Low-risk score (≥5): Patients exercising >10 metabolic equivalents with negative exercise ECG have excellent prognosis with limited need for downstream testing 1

Recommended Next Step: Stress Imaging

The appropriate workup is stress testing with an imaging modality—either exercise echocardiography or exercise myocardial perfusion imaging—rather than proceeding directly to invasive coronary angiography. 2

Why Imaging is Superior to Repeat Exercise ECG

• Exercise ECG alone has low sensitivity (58%) and specificity (62%) for detecting obstructive coronary artery disease 1
• Abnormal exercise ECG results remain specific indicators of obstructive CAD and are associated with future coronary revascularization and MI risk, but significant amounts of non-obstructive and obstructive CAD remain unrecognized without additional imaging 1
• Stress imaging provides superior diagnostic accuracy compared to ECG changes alone, particularly when baseline abnormalities are present 2, 3

Choice of Imaging Modality

Exercise echocardiography is preferred when: 4

• Patient can exercise adequately (≥6 minutes or ≥5 METs) 3
• No fasting required, but avoid heavy meals within 2-3 hours 4
• Avoid caffeine on day of test 4
• Widely available, low-cost, no ionizing radiation 4
• Detects myocardial ischemia by assessing regional wall motion abnormalities during stress 4

Exercise myocardial perfusion imaging is preferred when: 2

• Higher diagnostic accuracy needed for risk stratification 5
• Sensitivity of 85% and specificity of 90% for CAD detection 5
• Can identify "silent" infarcts not detected by ECG 5
• Allows risk stratification based on extent and severity of perfusion defects 5

When to Proceed Directly to Coronary Angiography

Skip stress imaging and proceed directly to invasive evaluation in these high-risk scenarios: 2

• High-risk Duke Treadmill Score (≤-11) with limiting symptoms 2
• Recurrent symptoms despite adequate medical therapy 2
• Heart failure present 2
• Serious ventricular arrhythmias during exercise 2

Additional Prognostic Markers Beyond ST Changes

These findings increase risk and urgency of evaluation: 2

• Exercise capacity: <5 METs or inability to achieve 85% maximum predicted heart rate 2
• Symptoms during exercise: Typical angina, especially at low workload 2
• Arrhythmias: Ventricular arrhythmias during exercise 2
• Blood pressure response: Excessive hypertension or BP drop during exercise 1

Common Pitfalls to Avoid

Do not repeat standard exercise ECG testing in patients with: 1, 2

• Baseline ST-segment depression ≥0.1 mV on resting ECG 1
• Left bundle branch block, paced rhythm, or Wolff-Parkinson-White syndrome 1
• Digitalis therapy 1

These baseline abnormalities fundamentally compromise diagnostic accuracy of standard exercise ECG, leading to both false-positive and false-negative results. 2

Do not defer all testing in low-risk patients: Even with low-risk Duke Treadmill Score, patients with abnormal exercise ECG may still require imaging for definitive evaluation, as significant CAD can remain unrecognized. 1, 2

Special Population Considerations

In low-risk symptomatic women: Exercise ECG was equally effective compared to exercise myocardial perfusion scintigraphy with similar 2-year incidence of major adverse cardiovascular events, providing significant diagnostic cost savings. 1 However, stress imaging should still be considered if exercise ECG is abnormal. 6

In patients with reduced functional capacity: Pharmacological stress testing with imaging (dobutamine or vasodilator stress) should be used if patient cannot exercise adequately. 2, 4