Acute coronary syndrome

Background

Definition

• Spectrum of syndromes resulting from myocardial ischemia
  • Unstable angina: no biochemical or EKG abnormalities, but increasing anginal symptoms
    • New-onset, severe angina
    • Angina at rest
    • Early post-MI angina
    • Post-revascularization angina
  • NSTEMI: biochemical abnormalities with or without EKG abnormalities
  • STEMI: biochemical abnormalities with ST elevation in 2 or more contiguous leads

Consensus Classification of Myocardial Infarction (MI)

• Type 1: spontaneous MI from plaque rupture, dissection, etc
• Type 2: demand ischemia
• Type 3: likely MI but patient died before biomarkers were drawn
• Type 4
  • Type 4a: PCI-related MI
  • Type 4b: stent thrombosis
• Type 5: CABG-related MI

Etiology

• Thrombosis: rupture of atherosclerotic plaque resulting in thrombus formation that occludes the lumen
• Stenosis: luminal narrowing from progressive atherosclerotic disease

Clinical Manifestations

• Angina
• RV infarct will present with
  • Hypotension
  • Right heart failure

Complications

• Cardiogenic shock
• LV aneurysm: clot, ventricular fibrillation, ventricular tachycardia
• Ischemic mitral regurgitation
• Dynamic outflow obstruction
• Rupture: early (<24h) or late (<7d)
  • Posterior papillary rupture
    • No murmur, but acutely looks very unwell with large V-wave
    • Needs urgent MVR
• VSD
• Free wall rupture: tamponade or PEA

Investigations

• EKG
  • If concern for inferior STEMI, get a 15-lead to rule out RV infarct
• Labs
  • Troponin
  • CK
  • AST
• Imaging
  • Coronary angiogram
  • Myocardial perfusion (MIBI)

Management

• TNK 0.53mg/kg IV bolus then transfer to PCI centre
• If RV infarct
  • Fluids and fluids
  • Consider inotropes