A patient reports an episode of chest pain last week that has since resolved. Which investigation best determines whether that pain was stable angina or a myocardial infarction?

Correct answer: C. Exercise (stress) test

• A. A CBC does not evaluate coronary perfusion. Cardiac TROPONIN identifies myocardial necrosis, but it normalizes within 7-10 days, so it is not useful for an event a week or more in the past.
• B. A chest radiograph evaluates lung fields, cardiac silhouette, and the mediastinum. It cannot detect coronary ischemia and is used mainly to exclude other causes of chest pain.
• C. CORRECT (best of the options for the stated purpose). An EXERCISE STRESS TEST provokes controlled myocardial demand and looks for ischemic ST-segment change or symptoms. It is the standard first-line non-invasive test to establish whether chest pain is anginal (demand ischemia from a fixed coronary stenosis) as opposed to non-cardiac. Coronary ANGIOGRAPHY is the definitive anatomic test but is invasive and reserved for patients with a positive or high-risk non-invasive result.
• D. A resting echocardiogram assesses chamber size, valves, and wall motion. It may show a regional wall-motion abnormality after a large infarct, but a normal resting study does not exclude angina.

Note: Timing drives the choice: ACUTE chest pain now = ECG + troponin. RETROSPECTIVE evaluation of resolved pain = stress test first, angiography if positive. A prior silent MI can also be detected as pathologic Q waves on a resting ECG.