A 58-year-old man with a history of hypertension presents with chest pain on exertion that is relieved by rest. Physical examination and resting ECG are normal. Which investigation is most appropriate to confirm the diagnosis of stable angina and assess the extent of coronary artery disease?

Explanation

## Investigation of Choice for Stable Angina Diagnosis ### Role of Exercise Stress Testing **Key Point:** Exercise stress test (treadmill test) is the first-line non-invasive investigation for diagnosis and risk stratification in suspected stable angina with a normal resting ECG. ### Why Exercise Stress Test? The exercise stress test: 1. Reproduces symptoms under controlled conditions 2. Detects ST-segment changes (≥1 mm horizontal or downsloping ST depression in ≥2 contiguous leads) 3. Assesses functional capacity and exercise tolerance 4. Provides prognostic information (Duke treadmill score) 5. Is non-invasive, widely available, and cost-effective **High-Yield:** A positive stress test (typical chest pain + ST depression) has ~70% sensitivity and ~80% specificity for significant coronary artery disease. ### Diagnostic Algorithm for Stable Angina ```mermaid flowchart TD A[Suspected stable angina]:::outcome --> B{Resting ECG normal?}:::decision B -->|Yes| C[Exercise stress test]:::action B -->|No| D[Consider imaging: Echo or stress imaging]:::action C --> E{Positive for ischemia?}:::decision E -->|Yes| F[Coronary angiography]:::action E -->|No| G[Low risk: Medical management]:::outcome F --> H[Revascularization if indicated]:::action ``` **Clinical Pearl:** Coronary angiography is the gold standard but is invasive and reserved for patients with positive non-invasive tests or high-risk features; it is not a first-line diagnostic test. ### Limitations of Other Investigations - **Resting ECG:** Often normal in stable angina; lacks sensitivity - **Troponin:** Elevated only in acute myocardial infarction, not in stable angina - **Chest X-ray:** Non-specific; used to exclude other causes of chest pain - **Coronary angiography:** Gold standard but invasive; reserved for therapeutic or high-risk diagnostic scenarios **Tip:** In patients unable to exercise (disability, deconditioning), pharmacologic stress testing (dobutamine, adenosine, or regadenoson) or imaging modalities (stress echocardiography, myocardial perfusion imaging, or coronary CT angiography) are alternatives.