Abstract 978: The Clinical Significance of Borderline Elevated Troponin-I Levels Across Different Assays
Background: Markedly elevated troponin I (TnI) is a strong predictor of adverse cardiac events. It is not clear if borderline elevations with different commercially available TnI assays provide similar prognostic information.
Methods: From 1/01 to 2/04, three different TnI assays (Beckman Access TnI, Beckman Access AccuTnI and Vitros ECI Troponin) were used to evaluate the peak TnI value in1094 consecutive patients admitted with suspected ACS/NSTEMI. Recommended cut-offs were used to differentiate borderline from marked elevations reported as consistent with myocardial infarction (MI). Clinical data and 30-day death/new MI were determined by chart abstraction.
Results: Demographics and cardiac risk factors were similar for the three groups. Frequency of borderline TnI ranged widely between the assays (18.7– 42.1%) but was significantly less with the Vitros ECI TnI assay (p<0.0001). Prognostic significance of borderline elevated TnI varied greatly by assay as well, with borderline Beckman Access AccuTnI elevations being predictive of adverse 30-day outcomes (OR=4.0, 95% CI=1.46 – 10.97, p-value=0.007), but not the other two assays. Borderline elevations were significantly associated with chronic renal insufficiency (CRI, serum Cr>1.5); the relationship to adverse 30-day outcomes and borderline elevations persisted after correcting for CRI in a multivariate logistic regression model.
Conclusions: Although borderline elevated troponin-I levels are common and significantly associated with chronic renal insufficiency, they do not all portend the same clinical prognosis. This study highlights the need for standardization of TnI levels across different assays.