Cardiac Enzymes and Protein Markers

Key points

• Myoglobin is the first marker to rise (1-2 h); troponin T and I have largely superseded the older enzymes
• CK-MB is the best marker of reinfarction: returns to normal after 2-3 days, whereas troponin T remains elevated for up to 10 days
• Kinetics (rise · peak · normal): myoglobin 1-2 h · 6-8 h · 1-2 d; CK-MB 2-6 h · 16-20 h · 2-3 d; CK 4-8 h · 16-24 h · 3-4 d
• Troponin T 4-6 h · 12-24 h · 7-10 d; AST 12-24 h · 36-48 h · 3-4 d; LDH 24-48 h · 72 h · 8-10 d
• Troponin T binds tropomyosin; troponin is a component of the thin filaments (with actin and tropomyosin) — thick filaments are primarily myosin