Long-term prognosis of low high-sensitivity cardiac troponin T in the emergency department compared with the general population.

Background: Long-term prognosis associated with low-high-sensitivity cardiac troponin T (hs-cTnT) concentrations in patients with chest pain is unknown. We investigated these prognostic implications compared with the general population.

Methods: All first visits to seven emergency departments (ED)s in Sweden were included from 9 December 2010 to 31 August, 2017 by patients presenting with chest pain and at least one hs-cTnT measured. Patients with myocardial injury (any hs-cTnT >14 ng/L), including patients with myocardial infarction (MI) were excluded. Standardised mortality ratios (SMRs) and standardised incidence ratios (SIRs) were calculated as the ratio of the number of observed to expected events. The expected number was computed by multiplying the 1-year calendar period-specific, age-specific and sex-specific follow-up time in the cohort with the corresponding incidence in the general population. HRs were calculated for all-cause mortality and major adverse cardiovascular events (MACE), defined as acute MI, heart failure hospitalisation, cerebrovascular stroke or cardiovascular death, between patients with undetectable (<5 ng/L) and low (5-14 ng/L) hs-cTnT.

Results: A total of 1 11 916 patients were included, of whom 69 090 (62%) and 42 826 (38%) had peak hs-cTnT concentrations of <5 and 5-14 ng/L. Patients with undetectable peak hs-cTnT had a lower mortality risk compared with the general Swedish population (SMR 0.83, 95% CI 0.79 to 0.87), with lower risks observed in all patients ≥65 years of age, but a slightly higher risk of being diagnosed with a future MI (SIR 1.39, 95% CI 1.32 to 1.47). The adjusted risk of a first MACE associated with low versus undetectable peak hs-cTnT was 1.6-fold (HR 1.61, 95% CI 1.53 to 1.70).

Conclusion: Patients with chest pain and undetectable hs-cTnT have an overall lower risk of death compared with the general population, with risks being highly age dependent. Detectable hs-cTnT concentrations are still associated with increased long-term cardiovascular risks.