Long-term prognosis associated with undetectable high-sensitivity cardiac troponin T concentrations in the emergency department

Abstract

Abstract Background The long-term prognostic implications of low or undetectable high-sensitivity cardiac troponin T (hs-cTnT) levels in patients presenting with chest pain in the emergency department (ED) have not been thoroughly studied. Furthermore, the prognosis has not been compared to the general population. Purpose This study aimed to investigate the long-term risk of all-cause mortality and cardiovascular outcomes in patients with chest pain but no myocardial injury, compared with the general population in Sweden. Methods Among all visits to 7 major EDs in Sweden from December 9, 2010 to August 31, 2017, we included the first visit by patients ≥18 years of age with chest pain and ≥1 hs-cTnT measurement. Visits in patients with myocardial injury (any hs-cTnT >14 ng/l), including those associated with a diagnosis of myocardial infarction (MI) were excluded. Standardized mortality ratios (SMRs) and incidence ratios (SIRs) were estimated to compare risks of death and future MI with the general population. Hazard ratios (HRs) with 95% CIs were calculated for comparisons of mortality and major adverse cardiovascular events (MACE) between visits with undetectable (<5 ng/l) and low (5-14 ng/l) hs-cTnT concentrations. Results A total of 112,694 visits were included, of which 69,571 (62%) and 43,123 (38%) occurred in patients with hs-cTnT <5 ng/l and 5-14 ng/l, respectively. All-cause mortality was overall lower compared to the standardized Swedish population (SMR 0.51, 95% CI: 0.49-0.54, and 0.88, 95% CI: 0.85-0.90), while risks of a future MI were higher (SIR 1.33, 95% CI: 1.25-1.42, and 1.53, 95% CI: 1.46-1.59). Hs-cTnT concentrations <5 ng/l were associated with a lower all-cause mortality in men ≥55 years and in women ≥65 years of age, respectively (figures 1 and 2). During a median follow-up of 6.4 years (IQR 4.8-8.0), 1769 (2.5%) and 5535 (13%) deaths occurred in patients with hs-cTnT <5 and 5-14 ng/l, respectively. The adjusted risks of death and MACE were 1.7- (HR 1.70, 95% CI: 1.60-1.80) and 1.6-fold (HR 1.63, 95% CI: 1.54-1.73) higher in patients with hs-cTnT 5-14 ng/l compared to patients with hs-cTnT <5 ng/l. Conclusions Patients with chest pain and low or undetectable hs-cTnT concentrations have an overall lower risk of death, but a higher risk of future MIs, compared with the age-standardized general population. In addition, detectable Hs-cTnT concentrations below the 99th percentile cutoff value are associated with long-term risks of death and MACE.Crude mortality rateStandardized mortality ratio