Combining Troponins T and I for AMI Diagnosis
What is the diagnostic performance of a combination of high-sensitivity (hs) cardiac troponin I (cTnI) and hs-cTnT for the early diagnosis of acute myocardial infarction (AMI)?
The authors compared the diagnostic performance of combining an hs-cTnI (Architect, Abbott) assay with an hs-cTnT (Elecsys, Roche) assay obtained at time of presentation in patients with suspected AMI. The optimal rule-out and rule-in thresholds were externally validated in a second large multicenter study. The results of this combination assay strategy were compared with the European Society of Cardiology (ESC) 0/1 and 0/3 hour algorithms.
There was a very high correlation between hs-cTnI and hs-cTnT concentrations at presentation (r = 0.89). A strategy of combining hs-cTnI and hs-cTnT concentrations did not increase overall diagnostic accuracy as compared with the individual isoforms. However, the combination improved the proportion of patients meeting criteria for very early rule-out, with approximately 50% of patients being ruled out at presentation.
A strategy of combining hs-cTnI and hs-cTnT assays may significantly increase the number of patients eligible for very early and safe rule-out, but did not improve accuracy of rule-in of AMI.
The use of hs troponin assays has markedly impacted the workup of patients with suspected AMI. The authors suggest that the combination of hs-cTnI and hs-cTnT can increase the proportion of patients who can be ruled out at presentation and thus save costs and emergency room crowding. The results of their study were based on a population with a very low incidence of AMI, and the true negative predictive value of this combination (and the resultant potential safety of discharging patients at presentation) would require validation in a larger population with a higher incidence of AMI before this approach can be adopted in wider clinical practice.
Keywords: Acute Coronary Syndrome, Algorithms, Biological Markers, Early Diagnosis, Emergency Service, Hospital, Myocardial Infarction, Patient Discharge, Protein Isoforms, Troponin I, Troponin T
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