Impact of implementation of the new highly sensitive cardiac troponin T (hsTnT) assay in a university hospital setting

Background. Troponin is recognized as the gold standard for diagnosisof myocardial infarction. The new hsTnT (Roche Diagnostics) has improved both analytical sensitivity and imprecision, lowering the diagnostic cut-off to 15 ng/L, corresponding to 99th percentile limit of our reference population. Methods. Recently, we replaced the 4th generation TnT assay (cut-off 0.03 μg/L) with hsTnT. Three months after the implementation, we performed an audit on the impact of hsTnT by comparing datawith the same period one year before. Results. After hsTnT implementation, a 5.4% increase of troponin tests was recorded.A positive result was found in 31.7% of TnT and in 58.7% of hsTnT (+85%), corresponding to 22.2% and 47.0% positive patients, respectively (P<0.0001).64% of hsTnT positive resultsfell in the 16-65 ng/L range, determined as negative with TnT.The number of tests per examination averaged 1.54±1.0 before and 1.67±1.1 after hsTnT implementation (P<0.0001). By auditingtroponin curves (i.e. at least two results during patient examination), 39.1% for TnT and 69.0% for hsTnT had at least one result positive (P<0.0001). However, when the positive curves were classified as typical/atypical according to the established reference change value (+46/-32%), the difference in percentage of positive curves displaying a typical marker release became not significant (17.2% for TnT vs. 20.5% for hsTnT, P=0.32). Conclusions. The introduction of hsTnT markedly increases the number of positive tests. Interestingly, our data show that in interpreting the almost doubled positive results, the evaluation of marker release may keep specificity at the same level of TnT.