According to NCSBN : CK-MB rises within 2 hrs of Acute MI, and stays elevated for a few days. Troponin rises within a few hrs of MI too, but stays elevated for a few weeks.
I’ve read somewhere that CK-MB is a definitive for Dx of acute MI b/c it’s specifically shows damage to cardiac muscle. CK-MM - damage to skeletal muscle.
Hope this helps
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