Background: The threshold of troponin elevation that stimulates changes in clinical decision making for patients with non-ST-segment elevation acute coronary syndromes (NSTE ACSs) has not been previously evaluated.
Methods: A total of 23 298 patients with NSTE ACSs from the CRUSADE (Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the ACC/AHA Guidelines) initiative were separated into categories of maximum troponin ratios (ratio of the highest recorded troponin value in the first 24 hours to the local laboratory troponin assay upper limit of normalization [ULN]).
Results: Unadjusted rates of in-hospital mortality increased from the group with troponin levels below the reference limit (maximum troponin ratio 0-1 x ULN; n = 5291) to those with minor (1-2 x ULN; n = 2499), intermediate (2-5 x ULN; n = 3825), and major (>5 x ULN; n = 11 683) elevations (-2.8% vs 4.6% vs 4.7% vs 6.0%). The use of early (<24 hours) aspirin, heparin, glycoprotein IIb/IIIa inhibitors, and beta-blockers was similar for the group with troponin levels below the reference limit compared with those with minor troponin elevations, and greater use of medications was demonstrated in patients with intermediate and major troponin elevations. Use of cardiac catheterization and percutaneous coronary intervention was higher in patients with troponin levels below the reference limit compared with those with minor troponin elevations, and procedures were used most frequently in patients with major troponin elevations. Similar patterns of care were demonstrated after excluding patients with chronic renal insufficiency.
Conclusions: Any degree of troponin elevation is associated with a higher risk of mortality for patients with NSTE ACSs, but guideline-recommended medical therapies are used more commonly only in patients with intermediate and major troponin elevations, whereas patients with troponin levels below the reference limit underwent invasive procedures more frequently than those with mild troponin elevations.