In an asymptomatic young adult without cardiovascular risk factors, are stress‑induced ST‑segment changes on an exercise ECG considered a normal finding?

ST-Segment Changes During Exercise in Asymptomatic Young Adults

In asymptomatic young adults without cardiovascular risk factors, certain ST-segment changes during exercise stress testing—particularly normalization of resting ST-segment elevation from early repolarization—are considered a normal physiologic finding and do not indicate coronary artery disease. 1

Normal ST-Segment Patterns in Young Adults

It is usual for young subjects with early repolarization to have normalization of resting ST-segment elevation during exercise. 1 This represents a benign physiologic response rather than pathology.

Key Distinguishing Features of Normal vs. Abnormal Responses

Abnormal (pathologic) ST-segment changes that suggest ischemia include: 1

• Horizontal or downsloping ST-segment depression ≥1.0 mm (0.1 mV) measured 60-80 ms after the J-point
• ST-segment elevation during exercise in leads without Q waves (suggests severe transmural ischemia from proximal coronary obstruction)
• ST-segment changes accompanied by chest pain, hypotensive blood pressure response, or complex ventricular arrhythmias

Equivocal or non-diagnostic findings include: 1

• Upsloping ST-segment depression ≥1.0 mm (does not usefully separate normal from abnormal)
• Any ST-segment depression <1.0 mm from baseline (defined as negative/normal)
• J-point depression only without persistent ST-segment depression

Clinical Context Matters: Pre-Test Probability

The predictive value of any ST-segment change is greatly influenced by the pre-test probability of coronary artery disease. 1 In young asymptomatic individuals without cardiac risk factors, the pre-test probability is very low (<15%). 1

An exercise ECG demonstrating ST-segment depression in a young asymptomatic person without cardiac risk factors is most likely a false-positive result, whereas the same finding in an elderly person with typical anginal symptoms is most likely a true positive result. 1

When Exercise Testing Is Appropriate in Young Adults

Exercise stress testing is reasonable in asymptomatic young adults (<30 years) primarily when: 1

• Evaluating congenital heart disease (e.g., aortic stenosis with mean Doppler gradient >30 mm Hg)
• Assessing exercise capability before athletic participation in those with known structural heart disease
• The patient has symptoms suggestive of coronary disease regardless of age

Routine screening of asymptomatic young adults without risk factors is not recommended. 1, 2

Common Pitfalls to Avoid

Do not interpret isolated ST-segment changes without considering: 1, 2

• Patient age and sex (women have higher false-positive rates)
• Presence or absence of cardiovascular risk factors (hypertension, diabetes, smoking, dyslipidemia, family history)
• Symptom status (chest pain, dyspnea, palpitations during testing)
• Exercise capacity achieved (inability to reach ≥85% maximum predicted heart rate or ≥5 METs reduces diagnostic accuracy)
• Blood pressure response (hypotensive response is high-risk)
• Baseline ECG abnormalities (left ventricular hypertrophy, bundle branch block, digitalis effect all cause false-positives)

Baseline ECG abnormalities that preclude accurate interpretation include left bundle-branch block, paced rhythm, Wolff-Parkinson-White pattern, left-ventricular hypertrophy with strain, ≥0.1 mV ST-depression at rest, or chronic digitalis therapy. 1, 2 These conditions lead to non-interpretable changes and high false-positive rates.

When Further Evaluation Is Warranted

Proceed to imaging stress testing (stress echocardiography, SPECT, PET, or CMR) when: 1, 2

• Exercise ECG results are inconclusive (patient fails to reach ≥85% age-predicted maximal heart rate without symptoms)
• Baseline ECG is uninterpretable
• High-risk features are present (ST-segment elevation, marked ST-depression, hypotensive response, sustained ventricular arrhythmias)

In the specific case of a young asymptomatic adult with ST-segment changes on exercise testing but no risk factors, coronary CT angiography may be considered to definitively rule out anatomic coronary disease if clinical suspicion persists. 3 However, this is rarely necessary in truly asymptomatic young individuals with normal functional capacity.