Aims To test the utility of a single copeptin determination at presentation to the emergency department (ED) as a short-term prognosis marker in patients with non-ST-elevation acute coronary syndrome (NSTEACS). To compare the results with those achieved with conventional troponin.

Methods A multicentric, prospective, observational, longitudinal, cohort study involving 15 Spanish EDs. Inclusion: consecutive patients with chest pain (<12 h) finally diagnosed of NSTEACS. Measurements: copeptin and troponin at arrival. Cut-off point for copeptin: 25.9 pmol/l. Follow-up: within 2 months after ED attendance to identify 30-day adverse events. Discriminatory capacity of copeptin and troponin was compared by receiver operating characteristic (ROC) curves.

Results We included 377 patients with NSTEACS. Adverse events: 11 (2.9%) patients died, 27 (7.2%) had an adverse coronary event, 14 (3.7%) had a stroke, and 48 (12.7%) a composite endpoint. The initial copeptine value was over 25.9 pmol/l in 114 patients, and they presented a higher mortality rate (OR: 4.2, (95% CI 1.2 to 14.8); p=0.03). This association disappeared after adjusting by clinical variables or troponin level. No significant differences were found for the remaining endpoints. The area under the curve  of the ROC curve of 30-day mortality was 0.73 (95% CI 0.58 to 0.87) for copeptin, and 0.80 (95% CI 0.73 to 0.87) for troponin.

Conclusions In patients with NSTEACS, determination of copeptin at presentation to the ED is associated with risk of death during the subsequent month. This association, however, disappears after adjusting by baseline features or troponin level, so copeptin does not add complementary prognostic information over that provided by troponin.