Clin. Lab. 3+4/2012 357 Clin. Lab. 2012;58:357-360 ©Copyright LETTER TO THE EDITOR Combination of Copeptin and Highly Sensitive Troponin I for Diagnosing Acute Myocardial Infarction at Emergency Department Admission GIUSEPPE LIPPI 1 , ROSALIA ALOE 1 , MARIELLA DIPALO 1 , GIANFRANCO CERVELLIN 2 1 U.O. di Diagnostica Ematochimica, Azienda Ospedaliero-Universitaria di Parma, Italy 2 U.O. Di Pronto Soccorso e Medicina d’Urgenza, Azienda Ospedaliero-Universitaria di Parma, Italy (Clin. Lab. 2012;58:357-360) KEY WORDS Acute myocardial infarction; highly-sensitive troponin; copeptin LETTER Copeptin is a stable fragment of arginine vasopressin (AVP) precursor, which physiologically contributes to the structural formation of AVP before its release into the bloodstream. There is increasing evidence support- ing a role of copeptin measurement for reducing the time taken to diagnose acute coronary syndrome (ACS) or acute myocardial infarction (AMI) in patients pre- senting with acute chest pain at the emergency depart- ment (ED), especially in combination with highly sensi- tive (hs) cardiac troponins, either hs-troponin T (hs- TnT) or hs-troponin I (hs-TnI). Giavarina et al. recently reported that copeptin provides significant incremental value on top of hs-TnI [1]. Giannitsis et al. also de- scribed that a strategy using copeptin with hs-TnT at prespecified cutoffs improves the ruling out of non-ST- segment elevation myocardial infarction (STEMI) as compared with using hs-TnT alone [2]. Conversely, Karakas et al. found that copeptin concentrations are not independently predictive of ACS and do not add diag- nostic value beyond that of hs-TnT measurements [3]. The opposite outcome of these studies led us to investi- gate whether copeptin measurement at the time of the patient’s admission at the emergency department (ED) might provide significant contributions to the diagnosis of AMI in combination with a novel, prototype hs-TnI immunoassay. The study population consisted in 56 consecutive pa- tients presenting at the ED of the Academic Hospital of Parma with chest pain. Blood samples were obtained at patient admission, within 180 minutes from chest pain onset. Cardiac TnI was measured with the prototype hsAccuTnI immunoassay on an Access 2 (Beckman Coulter Inc., Brea, CA, USA). The 99 th percentile reference limit and limit of detection are 8.6 ng/L and 2.1 ng/L, respectively [4]. Copeptin was measured with a commercial sandwich immuno- luminometric assay (LIA assay, CT-proAVP, Brahms AG, Germany), which has been described elsewhere [5]. The limit of detection has been determined to be 4.8 pmol/L [2]. The diagnosis of AMI was established ac- cording to the ESC/ACCF/AHA/WHF criteria [6] and was considered the primary endpoint. The incremental value of copeptin in the diagnostics approach was as- sessed by Receiver Operating Characteristic (ROC) curve analysis, with a level of statistical significance set at p<0.05. A final diagnosis of AMI was established in 9 out of the 56 patients (i.e., 16%). The ROC curve analysis of hs- AccuTnI alone exhibited an area under the curve (AUC) of 0.891 (95% CI, 0.775 - 1.000; p<0.001), whereas that of copeptin was 0.872 (95% CI, 0.755 - 0.989; p<0.001). A small but not significantly higher AUC (p=0.772) was observed for the combination of hs- AccuTnI and copeptin (AUC 0.898; 95% CI, 0.786 - 1.00; p<0.001) as compared with hs-AccuTnI alone (Figure 1). The novel hs-AccuTnI immunoassay exhibits a greater diagnostic performance on ED admission than that pre- viously reported by Karakas et al. for hs-TnT (AUC _____________________________________________ Letter to the Editor accepted November 27, 2011