A patient with an inferior wall myocardial infarction is at risk for reinfarction. Which laboratory finding would most strongly suggest reinfarction?

• A. A new rise in troponin levels
• B. Normal lipid panel
• C. Stable baseline troponin
• D. Decrease CK-MB

Answer: (A)

A new rise in troponin levels on serial testing is the clearest sign that another myocardial injury has occurred. Troponin I or T is highly specific for cardiac muscle damage, and after the first infarct troponin values typically rise and then fall; a renewed increase signals reinfarction due to a second event of necrosis.

Normal lipid panel doesn’t reflect acute myocardial injury, and a stable baseline troponin suggests no new injury. CK-MB can rise with reinfarction too, but troponin is more sensitive and specific, making a new troponin rise the strongest indicator of reinfarction.