A 62-year-old man develops recurrence of severe chest pain 18 hours after successful thrombolysis for inferior STEMI. To distinguish reinfarction from the expected post-thrombolytic enzyme washout rise, which cardiac biomarker is most appropriate?

• A Total CK
• B CK-MB fraction ✓
• C LDH
• D Myoglobin

Explanation

After successful reperfusion there is an early washout rise and peak of enzymes, making total CK and myoglobin unreliable for detecting reinfarction. CK-MB returns toward baseline faster than total CK, so a renewed rise of more than 50 percent above the previous value indicates reinfarction. LDH peaks late at 72 hours or beyond and has poor specificity, and myoglobin rises too early and nonspecifically to be useful here.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.