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Small Changes in Troponin T Levels Are Common in Patients With Non-ST-Elevation Myocardial Infarction and Are Linked to Higher Mortality
Study Questions:
What is the frequency and clinical importance of change in high-sensitivity cardiac troponin (hs-cTn) in patients with non-ST-segment elevation myocardial infarction (NSTEMI)?
Methods:
Serial samples of cTnT were measured with an hs-cTnT assay in 1,178 patients with a final diagnosis of NSTEMI who presented within 24 hours of symptom onset. Patients with an alternate diagnosis that could be associated with an elevated troponin such as atrial fibrillation or congestive heart failure were excluded.
Results:
A rise in hs-cTnT levels during the hospital stay was observed in 80% of the NSTEMI patients with a median relative hs-cTnT change of 128%. After 6 hours of observation, the relative change in the hs-cTnT level remained <20% in 26% of the patients and the absolute change <9 ng/L in 12% of the NSTEMI patients. A relative hs-cTnT change <20% was linked to higher long-term mortality across quartiles (p = 0.002) and in multivariate analyses (hazard ratio, 1.61 95% confidence interval, 1.17-2.21; p = 0.004), whereas 30-day mortality was similar across quartiles of relative hs-cTnT change.
Conclusions:
The authors concluded that stable hs-TnT levels are common in patients with a clinical diagnosis of NSTEMI, and these patients have similar mortality compared with those with larger changes in hs-cTnT.
Perspective:
The diagnostic evaluation of patients with chest pain will change once the hs-Tn assays become routine part of clinical practice. A relative change of 20-23% and an absolute change of 7-9 ng/L have been suggested as cut-off points in diagnosing NSTEMI. In this small study, no difference in outcome was noted among the subset of patients who had smaller changes in troponin levels. The study is underpowered to rule out a survival difference, and the results need to be corroborated in larger studies before these findings are applied to routine practice.
Keywords: Myocardial Infarction, Biomarkers, Troponin I, Cardiovascular Diseases, Troponin T, Electrocardiography
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