Acute Coronary Syndrome – CF, dx, ddx

Clinical features

Diagnosis

ECG changes

• ST depression and T-wave inversion – highly suggestive of NSTE-ACS
• STEMI – complete occlusion of a coronary vessel
• Results in persistent ST-elevation
• Or LBBB

REMEMBER

• ST Elevation – infarction (irreversible damage)
• ST Depression – ischemia (reversible with prompt tx)

Biochemical markers

• Cardiac troponin complex
  • Troponin levels  rise from 2-24hrs after pain, peak at 24-48hrs, and return to baseline after 5-14 days
  • Troponins I, T, C
    • T – attaches the complex to tropomyosin
    • C – binds Ca during excitation-contraction
    • I – inhibits the myosin binding site on actin
  • Normal serum troponin – <5ng/L
  • ↑ Serum troponin – increased mortality in ACS patients
• CK-MB – raised after muscle trauma
  • Levels drop back to normal after 36-72hrs
  • Replaced by troponin testing, but can be used to determine re-infarction

Differential diagnosis

Cardiac

• Angina
• Pericarditis
• Myocarditis
• Aortic dissection

Pulmonary

• PE
• Pneumothorax

Oesophageal

• Reflux or spasm
• Tumour
• Oesophagitis

Risk stratification – Grace Score

• Risk stratification is important because it guides the use of pharmacological and interventional treatment