A 52-year-old woman with a history of smoking and diabetes mellitus presents with recurrent episodes of chest pain at rest over the past 2 days, each lasting 10–15 minutes and relieved by sublingual nitroglycerin. Her 12-lead ECG during pain shows symmetric T-wave inversion in leads V2–V4 that normalizes between episodes. Troponin I is negative. Which investigation is most specific for detecting the culprit lesion and guiding revascularization strategy in this patient with unstable angina?

Explanation

## Investigation of Choice for Culprit Lesion Identification in Unstable Angina **Key Point:** Coronary angiography is the gold standard for identifying the culprit lesion in unstable angina and is both diagnostic AND therapeutic, allowing immediate revascularization if indicated. ### Clinical Context: Why Angiography in This Case? **Patient profile:** - Unstable angina: rest angina with dynamic ECG changes (T-wave inversion) and negative troponin - High-risk features: recurrent episodes, smoking, diabetes - Dynamic ECG: T-wave changes that normalize between episodes (hallmark of transient ischemia) **High-Yield:** Unstable angina with dynamic ECG changes and high-risk features (diabetes, smoking) warrants early invasive strategy (angiography within 24 hours) per ACC/AHA 2014 guidelines. ### Why Coronary Angiography Is Superior 1. **Specificity**: Directly visualizes coronary anatomy and identifies the culprit stenosis 2. **Therapeutic**: Allows immediate PCI if flow-limiting lesion found 3. **Prognostic**: Identifies multivessel disease and guides revascularization strategy 4. **Risk assessment**: SYNTAX score and other angiographic indices inform prognosis 5. **Guideline-concordant**: Class IIa recommendation for early invasive strategy in unstable angina with high-risk features ### Comparison with Alternatives | Investigation | Specificity for Culprit | Therapeutic? | Role in Unstable Angina | Timing | |---|---|---|---|---| | **Coronary angiography** | 100% — direct visualization | Yes (PCI possible) | Gold standard for diagnosis & therapy | 24 hrs (high-risk) | | Stress testing | Detects ischemia, not anatomy | No | Contraindicated in acute phase | Post-stabilization | | Cardiac MRI | Detects myocardial scar | No | Research tool; not for acute diagnosis | Delayed | | IVUS | Detailed plaque morphology | No | Adjunct to angiography; not first-line | During angiography | **Clinical Pearl:** In unstable angina with dynamic ECG changes, stress testing is **contraindicated** during the acute phase because it may precipitate recurrent ischemia or infarction. Angiography is preferred over non-invasive imaging because it is both diagnostic and immediately therapeutic. ### Mnemonic: Early Invasive Strategy in ACS **EARLY** = **E**levated risk features → **A**ngiography → **R**evascularization → **L**ower mortality → **Y**ield benefit **Warning:** Do NOT perform stress testing in a patient with active unstable angina. The patient is still in the acute ischemic window and at high risk of recurrent events; stress testing may be harmful.