Clinical Significance Of Borderline Cardiac Troponin (cTnI) In Patients Presenting With Acute Coronary Syndrome Who Are Referred For Cardiac Catheterization

Background: Given the heterogeneity of troponin values and cut-off points, it is not clear what magnitude of troponin elevation is essential for decision-making. Borderline troponin values are particularly challenging for physicians needing to triage patients. This study was designed to evaluate the clinical significance of borderline cardiac troponin (cTnI) in patients presenting with acute coronary syndrome who are referred for cardiac catheterization. Methods: The study population was derived from patients presenting to the Newark Beth Israel Medical Center (Newark, New Jersey) emergency room, who were admitted to telemetry/critical care unit and who subsequently went for cardiac catheterization. A fraction of these patients (total 865) had simultaneously collected samples of CK-MB and cTnI. Post hoc analysis of prospectively gathered clinical and laboratory data was tabulated on these patients. Patients with borderline cTnI values (0.5-2.0 ng/ml) were the focus of this analysis. In our institution the normal range for cTnI is 0-1.5 ng/ml. Results: Fifty patients met the above criteria. 37/50 (74%) had significant coronary artery disease. 13(26%) patients had luminal irregularities; coronary artery disease that was clear-cut but nonobstructive. Zero patients had smooth, normal coronary arteries. Conclusion: Patients with high clinical index for coronary artery disease, who are referred for cardiac catheterization and have a borderline elevation in cTnI, have a strong likelihood of coronary artery disease.