Outcomes associated with small changes in normal-range cardiac markers

Area of Science:

• Cardiology
• Biomarkers
• Emergency Medicine

Background:

• Troponin concentrations above institutional cutpoints define acute myocardial necrosis.
• The clinical significance of troponin fluctuations below these cutpoints remains unclear.
• This study investigates the association between sub-threshold troponin changes and acute coronary syndrome (ACS).

Purpose of the Study:

• To evaluate the association between troponin fluctuations below the upper limit of normal and the occurrence of acute coronary syndrome (ACS).

Main Methods:

• Post hoc analysis of the Internet tracking registry of ACS (i*trACS) dataset.
• Included patients (≥18 years) with suspected ACS and at least two cardiac marker measurements (troponin T, troponin I, or CK-MB) within 6 hours, both below the institutional upper limit of normal.
• Defined marker change as >15% fluctuation; ACS defined as positive stress test, myocardial infarction, revascularization, or 30-day death.

Main Results:

• 2162 of 17,713 patient visits met inclusion criteria.
• Increasing troponin levels below the upper limit of normal were associated with significantly increased odds of ACS (OR, 3.6; 95% CI, 1.4-9.2).
• Neither changing creatine kinase-MB (CK-MB) nor decreasing troponin levels showed an association with increased ACS odds.

Conclusions:

• Subtle increases in troponin concentration below the established upper limit of normal are linked to a higher likelihood of acute coronary syndrome (ACS).
• These findings suggest that monitoring minor troponin changes may improve early diagnosis of ACS.