Combination of copeptin and troponin assays to rapidly rule out non-ST elevation myocardial infarction in the emergency department

Objectives: The aim of this study was to analyze the diagnostic accuracy and the clinical usefulness of the combination of troponin I (cTnI) and copeptin measured at presentation with an automated assay to rapidly rule out non-ST elevation myocardial infarction (NSTEMI) in patients with suspected cardiac chest pain presenting to an emergency department (ED).

Methods: This study was an ancillary analysis of a prospective observational study. Copeptin and cTnI levels were sampled at presentation in 641 consecutive patients admitted to the ED for chest pain with onset within the last 12 hours and without ST elevation on a 12-lead electrocardiogram (ECG). Copeptin was measured with an automated assay and troponin with conventional assay. The performance of a combination of cTnI and copeptin for NSTEMI diagnosis was studied, the clinical utility was assessed by multivariate analysis, and an area under the curve (AUC) calculation was used to determine accuracy.

Results: NSTEMI was diagnosed in 95 patients (15%). The sensitivity and negative predictive value (NPV) of the combination of copeptin and cTnI measures were 90.4% (95% confidence interval [CI] = 88.2% to 92.7%) and 97.6% (95% CI = 96.4% to 98.7%) versus 55.3% (95% CI = 51.5% to 59.2%) and 92.8% (95% CI = 90.8% to 94.8%) with cTnI alone. The AUC of the combination of copeptin and cTnI was 0.89 (95% CI = 0.85% to 0.92%) and was significantly higher than the AUC of cTnI alone (0.77, 95% CI = 0.72% to 0.82%, p < 0.05). The patient classification was slightly improved when copeptin was added to the usual diagnostic tools used for NSTEMI management.

Conclusions: In this study, determination of copeptin, in addition to cTnI, improves early diagnostic accuracy of NSTEMI. However, the sensitivity of this combination even using a conventional troponin assay remains insufficient to safely rule out NSTEMI at the time of presentation.