Performance Of High-Sensitivity Cardiac Troponin T In Etiologic Diagnosis After Out-Of-Hospital Cardiac Arrest

Purpose: Early identification of the cause of out-of-hospital cardiac arrest (OHCA) remains a challenge. Our aim was to determine whether high-sensitivity cardiac troponin T (HsTnT) was useful to diagnose a recent coronary artery occlusion as the cause of OHCA. Methods: Retrospective study including OHCA patients evaluated by systematic coronary angiogram at hospital admission. HsTnT was assessed at ICU admission. Predictive factors of a recent coronary occlusion were identified by logistic regression. Net reclassification improvement (NRI) was calculated to estimate the potential enhancement of prediction with HsTnT. Results: During the 5 years study period, 272 patients (median age 60y, 76.5% men) were included, and a culprit coronary occlusion was found in 133 (48.9%). Median HsTnT at admission was 551 (IQR 203-2551) ng/l, up to three times higher in patients with compared to those without a recent coronary occlusion (1184 vs. 351 ng/l; p<0.0001). The optimum HsTnT cut-off to predict a recent coronary occlusion was 575 ng/l (sensitivity 65.4%, specificity 65.5%). In multivariate analysis, current smoking (OR 3.2 95%, 95%CI 1.62-6.33), time from collapse to BLS < 3 minutes (OR 2.11, 95%CI 1.10-4.05), initial shockable rhythm (OR 5.29, 95%CI 2.06-13.62), ST-segment elevation (OR 2.44, 95%CI 1.18-5.03), post-resuscitation shock onset (OR 2.03, 95%CI 1.01-4.07) and HsTnT ≥ 575ng/l (OR 2.22, 95% CI 1.16-4.27) were associated with the presence of a recent coronary occlusion. The AUROC curves of the multivariate model identified above were not statistically better than those of the same model with established risk factors but without HsTnT (AUROC curves= 0.78 vs. 0.79; p=0.23). Nevertheless, adding HsTnT to established risk factors of recent coronary occlusion identified above provided a non-significant NRI of -0.43%. Reclassification was not better in the subgroup of patients without ST-segment elevation (NRI= 0.105±0.078, p=0.18). Conclusions: Admission HsTnT is increased after OHCA and is an independent factor of a recent coronary occlusion. However, HsTnT does not seem to be a strong enough diagnostic tool to select candidates for emergent coronary angiogram in OHCA survivors.