It is crucial to rapidly identify cardiac ischemia in the care of patients with suspected acute coronary syndrome (ACS). Cardiac troponins are a major factor in the diagnostic of myocardial infarction. New methods have been developed to improve the accuracy of the assay and determine low troponin concentrations. Elecsys® (highly sensible T troponin) TnT-HS assay is supposed to help early detection of myocardial infarction after onset of symptoms. It should therefore shorten the transit time to emergencies by a more rapid intervention or a faster return home. The aim of the study is to compare TnT-HS assay to the standard troponin assay in the detection of early cardiac ischemia in patients with ACS.

Patients with suspected ACS with 2/2 negative results of conventional troponin I assay and 1/3 positive result of highly sensitive troponin assay will have a non invasive cardiac Rb82 PET/CT performed within 24 hours of admission. This exam is recognized by Associations of cardiology for its high sensibility and specificity in coronary disease detection.

Inclusion Criteria:

• chest pain of ≥ 5 minutes during the last 24 hours, or other symptoms suggestive of ACS (unstable angina or NSTEMI) with 2 negative standard troponin values(<0.09 µg/L)
• age ≥ 18

Exclusion Criteria:

• patients with ST- segment elevation myocardial infarction (STEMI)
• detection of TnI standard values > 0.09 (limit of positivity) in one of two blood samples (T0 and T6)
• detection of heart disease or extra-cardiac disease that could explain the elevated conventional troponin values
• presence of major organ dysfunction, infection or major underlying medical condition that could compromise the patient's ability to perform a stress test for myocardial ischemia
• cancer with prognosis < 6 months

Patients presenting to the emergency with chest pain suspect of acute coronary syndrome