A 60-year-old man develops recurrent chest pain 14 hours after successful primary PCI for STEMI. The treating team suspects reinfarction. His baseline troponin I was still rising at the time symptoms recurred. Which biomarker strategy is most appropriate to diagnose reinfarction in this setting?
- A Measure CK-MB mass; a new rise of 20 percent or more above the previously falling value supports reinfarction ✓
- B Repeat troponin I immediately; a rise above the previous value confirms reinfarction
- C Measure myoglobin, since it rises fastest and is specific for myocardial necrosis
- D Repeat LDH isoenzymes, since LDH remains elevated longest after infarction
Correct answer: A. Measure CK-MB mass; a new rise of 20 percent or more above the previously falling value supports reinfarction
Explanation
When troponin is still rising or plateauing after the index event, it cannot distinguish new necrosis from ongoing evolution, so a short-lived marker such as CK-MB is preferred. B new increase of 20 percent or more above a previously falling CK-MB value indicates reinfarction. Myoglobin lacks cardiac specificity, and LDH peaks days later with poor specificity, making both unsuitable for early reinfarction diagnosis.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.