The purpose of a cardiac stress test is to assess how the heart responds to increased workload, unmasking ischaemia or exercise-induced arrhythmias.
Methods to increase myocardial oxygen demand include:

Exercise Stress Test: Patient walks/runs on a treadmill with increasing incline/speed. ECG, blood pressure, and symptoms are monitored. May be combined with radionuclide scans (thallium, SPECT, PET).
Dobutamine Stress Echocardiography: Used in those unable to exercise. Dobutamine infusion ↑ heart rate/contractility. Echo assesses regional wall motion changes as a marker of ischaemia.

Stress testing can diagnose IHD, risk-stratify patients, guide need for angiography/revascularisation, and detect arrhythmias in a controlled setting.

📌 Indications

Diagnostic: Suspected IHD, unexplained chest pain, or arrhythmias. May require stopping beta-blockers/antianginals for accurate IHD assessment.
Prognostic: Post-MI evaluation, pre-operative cardiac risk, exercise capacity in heart failure, and detection of exercise-induced arrhythmias.

⚠️ Contraindications

Absolute: Recent MI (<48 hrs), suspected unstable angina, severe aortic stenosis, acute pulmonary oedema, severe uncontrolled hypertension, dangerous arrhythmias, inability to exercise safely.
Relative: Frailty, hypertrophic cardiomyopathy, significant fall risk.
Non-Diagnostic Situations: LBBB, paced rhythm, complete heart block.

📝 Process

Explain test, obtain consent, and ensure IV access/resus facilities if pharmacological stress is planned.
Attach ECG leads (adjusted to torso), record baseline ECG, BP, HR.
Exercise protocol: treadmill/bicycle with staged increases every 3 minutes. Monitor vitals at each stage.
Target HR:
- Males → 220 − age
- Females → 210 − age
Aim is 85% of predicted maximum.
Combine with radionuclide imaging if assessing perfusion:
- Fixed defect: infarction scar.
- Reversible defect: inducible ischaemia.

✅ Positive Test Indicators

Horizontal/downsloping ST depression ≥2 mm (esp. in V5).
Exercise-induced chest pain corresponding to ECG changes.
Fall in BP during exercise (poor prognostic sign).
Low exercise tolerance with early onset of symptoms/ECG changes → worse outcome.
Exercise-induced VT → mandates further cardiology workup.

💡 Teaching Pearls

Stress tests are most useful in patients with intermediate pre-test probability of IHD (not very low or very high).
ECG changes alone are less specific - coupling with imaging improves diagnostic accuracy.
Always consider patient safety - stress tests can provoke significant ischaemia or arrhythmia → resuscitation facilities must be available.

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Exercise stress test

🫀 About

📌 Indications

⚠️ Contraindications

📝 Process

✅ Positive Test Indicators

💡 Teaching Pearls

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