Low-level troponin elevations following a reduced troponin I cutoff: Increased resource utilization without improved outcomes.

Objective: The study sought to evaluate changes in mortality and resource utilization in patients with low level troponin elevations following a reduction in the cutoff for normal troponin I (TnI) from 0.5 ng/mL to the 99th percentile (0.06 ng/mL).

Methods: This was an interrupted time series comparing emergency department (ED) patients with possible acute coronary syndrome (ACS) and TnI values 0.06-0.5 ng/mL before and after an institutional decrease in the TnI cutoff. The primary outcome was overall mortality at 90 days. Secondary outcomes included rates of rehospitalization, subsequent ACS, and coronary intervention within 90 days, as well as rates of anticoagulation, cardiology consultation, cardiac testing, and coronary intervention during the index visit. Outcomes for the pre-cutoff change group (control) and post-cutoff change group (post) were compared using tests of proportions and odds ratios.

Results: The study included a total of 1058 subjects with 529 in each cohort. No significant differences in 90 day outcomes were observed between groups, including mortality (13.2% post vs 14.1% control, OR 0.93 [95% CI: 0.65-1.34], p = 0.705). During the index visit, the post-group demonstrated higher rates of cardiology consultation (55.4% vs 41.2%, OR 1.77 [1.39-2.26], p < 0.0001) and cardiac stress testing (16.4% vs 10.6%, OR 1.66 [1.16-2.38], p = 0.006), but no significant differences in coronary intervention or short-term mortality were observed.

Conclusion: A reduction in the TnI cutoff to the 99th percentile did not change mortality or rates of coronary intervention in ED patients with low level troponin elevations, but significantly increased the use of cardiology resources.