Overview
Definition
Part of the Acute Coronary Syndrome (ACS) spectrum characterized by myocardial ischemia without ST-segment elevation. NSTEMI involves myocardial necrosis (elevated troponins), whereas Unstable Angina does not.
Epidemiology
More common than STEMI. High risk of short-term adverse cardiac events if untreated.
Etiology & Risk Factors
- Rupture of an atherosclerotic plaque leading to partial thrombosis/occlusion of a coronary artery
Clinical Symptoms
- Chest pain occurring at rest or with minimal exertion
- Pain lasting > 20 minutes
- New-onset severe angina
- Crescendo angina (increasing in frequency/duration)
Clinical Approach
Diagnosis
- ECG: ST-segment depression or T-wave inversion (or normal)
- Cardiac Biomarkers: Elevated High-Sensitivity Troponin indicates NSTEMI; Normal Troponin indicates Unstable Angina
Management
- Antiplatelets: Aspirin + P2Y12 inhibitor (Clopidogrel/Ticagrelor)
- Anticoagulation: Heparin or Enoxaparin
- Anti-ischemic: Beta-blockers, Nitrates
- Early invasive strategy (Cardiac Catheterization within 24h) for high-risk patients (high GRACE/TIMI score)
Complications
- Progression to STEMI
- Heart Failure
- Cardiogenic Shock
- Arrhythmias