The aim of this study is to demonstrate that a combined troponin and copeptin assay can exclude non-ST+ ACS in patients with chest pain less than 6 hours old.

Chest pain accounts for about 10% of emergency service visits, which represents between 6 and 8 million visits per year in the United States and 15 million in Europe. Depending on the series, coronary etiology is found in 10 to 50% of cases.

Two types of coronary syndrome are distinguished according to the existence of a pathological change in the electrocardiogram.

ST+ acute coronary syndrome is a diagnosis based on the association of chest pain associated with an electrocardiogram change in the form of ST-segment elevation in a systemic territory corresponding to the complete obstruction of an artery of the coronary network.

Non-ST+ coronary syndrome is more difficult to diagnose, as the ECG is not pathological or cannot be interpreted due to the presence of conduction disorders. The diagnosis is currently based on the pathological increase of a specific myocardial biomarker in the blood: troponin.

If the pain is recent (less than six hours) the troponin measured on arrival may be falsely negative, and therefore requires a second measurement 3 hours after the first one (this is the troponin cycle). This second test therefore leads to a longer stay for patients requiring it and contributes to the saturation of the emergency service.

Copeptin is an endogenous stress biomarker that rises immediately during a myocardial infarction and decreases rapidly. Unlike troponin, this marker is not myocardial specific and its level can rise in the blood for many reasons, which is why this marker cannot be used alone in the diagnosis of non-ST+ acute coronary syndrome (non-ST+ ACS or ST- ACS).

The hypothesis would be that the association of a copeptin assay with the initial troponin assay could, if both markers are below pathological thresholds (Troponin < 16ng.dL), eliminate the diagnosis of acute coronary syndrome from the first assays and thus avoid the second troponin assay 3 hours after the first. The patient would reduce the time spent in the emergency and would thus reduce the number of patients in the emergency service.

Inclusion Criteria:

• Patient ≥18 years old
• Presenting at the Pontoise emergency department by their own means / ambulance or patients taken care of by the SMUR and referred to the NOVO hospital - Pontoise site
• Chest pain less than 6 hours old
• Chest pain suggestive of ACS (compressive, intense pain, radiating into the arm and neck, mid-thoracic, left thoracic or epigastric location)
• Non-contributory ECG (no ST elevation, presence of bundle branch block)
• Informed and having expressed no objection
• Beneficiary of a social security system (or entitled person)

Non -Inclusion Criteria:

• Sus ST-segment shift on ECG (ACS ST+)
• Intermittent pain/unclear onset time
• Pregnant woman
• Pain in the context of trauma
• Patient under guardianship
• Patient does not speak or understand French

Exclusion Criteria:

• Non-ultrasensitive troponin measurement positive during the 1st SMUR sampling (> 0.08 ng.dL)
• Patient not referred to the NOVO hospital - Pontoise site by the SMUR