A 58-year-old man with diabetes and hypertension presents to the emergency department with acute onset chest pain radiating to the left arm for 45 minutes. On examination, he is diaphoretic with BP 145/92 mmHg and HR 102/min. A 12-lead ECG shows ST elevation in leads II, III, and aVF. What is the investigation of choice to confirm the diagnosis and guide immediate management?

## Investigation of Choice in STEMI **Key Point:** Coronary angiography is the gold standard investigation and therapeutic intervention in acute STEMI. It serves dual purpose: diagnostic confirmation and immediate revascularization via primary percutaneous coronary intervention (PCI). ### Why Coronary Angiography? 1. **Diagnostic accuracy**: Directly visualizes coronary anatomy and identifies the culprit lesion 2. **Therapeutic capability**: Allows immediate PCI with stent placement 3. **Time-sensitive**: Should be performed within 90 minutes of first medical contact (door-to-balloon time) 4. **Risk stratification**: Identifies extent of disease and collateral circulation ### Clinical Context This patient has: - Acute ST elevation in inferior leads (II, III, aVF) → **inferior wall STEMI** - Likely right coronary artery (RCA) or left circumflex (LCx) occlusion - Hemodynamic instability (tachycardia, hypertension) - Requires urgent reperfusion therapy **High-Yield:** In primary PCI-capable centers (which should be the standard in India), coronary angiography with immediate PCI is superior to thrombolysis for STEMI [cite:Harrison 21e Ch 297]. ### Timeline ```mermaid flowchart TD A[STEMI diagnosed on ECG]:::outcome --> B{PCI-capable center?}:::decision B -->|Yes| C[Coronary angiography + PCI]:::action B -->|No| D[Thrombolysis + transfer]:::action C --> E[Door-to-balloon < 90 min]:::outcome D --> F[Door-to-needle < 30 min]:::outcome ``` **Clinical Pearl:** Troponin elevation (occurs 3-4 hours post-infarction) confirms myocardial necrosis but does NOT guide acute management — angiography is needed immediately.