A 58-year-old man with hypertension and dyslipidemia presents to the emergency department with chest pain of 3 hours duration. The pain is substernal, radiating to the left arm, and associated with diaphoresis. His initial ECG shows ST depression in leads II, III, aVF, and V3–V4 with T-wave inversion. Troponin I at presentation is negative. Vital signs are stable. What is the most appropriate immediate next step in management?

Explanation

## Clinical Context This patient presents with acute coronary syndrome (ACS) with high-risk features: typical ischemic chest pain, dynamic ECG changes (ST depression and T-wave inversion in multiple territories), and hemodynamic stability. Although troponin is negative at presentation, this does NOT exclude ACS — troponin can be negative in the first 3 hours of symptom onset. ## Key Point: **Early dual antiplatelet therapy (DAPT) and anticoagulation are indicated in NSTEMI/unstable angina regardless of initial troponin negativity.** The presence of ischemic ECG changes and typical symptoms is sufficient to initiate treatment. ## High-Yield: **Timing of coronary angiography in NSTEMI:** - **High-risk features** (recurrent ischemia, hemodynamic instability, ECG changes, elevated troponin, heart failure): angiography within **24 hours** (preferably within 12 hours) - **Intermediate-risk features**: angiography within **24–72 hours** - **Low-risk features**: may defer or perform stress testing This patient has high-risk features (ST depression in multiple territories, ongoing symptoms), warranting urgent angiography within 24 hours. ## Management Algorithm ```mermaid flowchart TD A[Chest pain + ECG changes ± troponin]:::outcome --> B{High-risk features?}:::decision B -->|Yes: ST depression, T-wave inversion, recurrent pain| C[Aspirin + Clopidogrel loading]:::action C --> D[Unfractionated heparin or LMWH]:::action D --> E[Angiography within 24 hours]:::action B -->|No: stable, low-risk| F[Observation + serial troponin]:::action F --> G[Stress test or delayed angiography]:::action E --> H[PCI if culprit lesion identified]:::action ``` ## Clinical Pearl: **Troponin negativity in the first 3 hours does not rule out ACS.** Serial troponin measurement (at 3 and 6 hours) is standard, but treatment should not be delayed pending results if clinical and ECG findings are suggestive. ## Rationale for Correct Answer - **Aspirin 325 mg** + **Clopidogrel 600 mg loading dose**: dual antiplatelet therapy is the foundation of NSTEMI management - **Unfractionated heparin**: anticoagulation reduces thrombotic events - **Angiography within 24 hours**: indicated by high-risk ECG changes and typical ischemic symptoms This approach follows the 2014 ACS guidelines and is the standard of care in Indian cardiology practice.