LAUSR

BACKGROUND Cardiac troponins (cTn) are essential in the diagnostic assessment of non-ST-segment-elevation acute coronary syndrome (NSTE-ACS). Elevated concentrations of cTnT and cTnI predict cardiovascular events in non-acute settings, but the individual troponin isotype association with long-term mortality in patients with suspected unstable angina pectoris (UAP) is less clear. METHODS Patients hospitalized with chest pain between June 2009 and December 2010 were included in the Akershus Cardiac Examination 3 Study and followed for median 6.6 (IQR 6.2-7.1) years. The index diagnosis was adjudicated by an independent committee as NSTE-myocardial infarction (NSTEMI), UAP or non-ACS. Blood samples were collected within 24 hours of admission and analyzed with high sensitivity assays for cTnT (hs-cTnT, Roche) and cTnI (hs-cTnI, Singulex). RESULTS Of 402 patients included, 74 (18%) were classified as NSTEMI, 88 (22%) UAP and 240 (60%) non-ACS. hs-cTnI concentrations were detectable in all patients (median 3 [IQR 1-11] ng/L), while hs-cTnT concentrations were above the level of blank in 205 (51%) (median 3 [IQR 3-16] ng/L). In patients with UAP, both log2-transformed hs-cTnT and hs-cTnI were associated with all-cause mortality in analyses that adjusted for other risk factors: HR 2.40 [95% CI 1.75-3.30], p<0.001 and HR 1.44 [1.14-1.81], p=0.002. There were no significant sex-dependent differences in the association between hs-cTnT or hs-cTnI and outcome. Time dependent receiver-operating characteristics area under the curve was 0.85 (95% CI 0.79-0.92) for hs-cTnT and 0.74 (0.64-0.84) for hs-cTnI, p=0.008 for difference between values. CONCLUSIONS Higher concentrations of hs-cTnT and hs-cTnI were both associated with all-cause mortality in patients with UAP, but the association with outcome was stronger for hs-cTnT than for hs-cTnI.