The rising number of patients with chest pain without myocardial infarction has made accurate diagnosis important. Unnecessary invasive coronary angiographies are increasingly prevalent. These are both costly and lead to rare but serious adverse events. Recent studies suggest cardiac Troponin I is more cardiac specific than cardiac Troponin T. In this study we will investigate whether using cardiac Troponin I lead to fewer unnecessary procedures in clinical practice (i.e. invasive coronary angiography and non-invasive tests)

Inclusion Criteria:

• Admitted to either Herlev-Gentofte or Amager-Hvidovre Hospital
• Clinically suspected of NSTEMI
• Referred to invasive coronary angiography (ICA)
• Recieved at least one measurement of either troponin

Exclusion Criteria:

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Two large acute medical centers will include patients for this study, one that routinely use cTnT (Hvidovre Hospital) and one that routinely uses cTnI (Herlev Hospital).

Each center will include consecutive patients over a period of 5 months clinically suspected of non-ST segment elevation myocardial infarction (NSTEMI). These patients will undergo serial measurement of either cardiac troponin T (cTnT) or cardiac troponin I (cTnI) as is standard practice. In addition to regular their lab tests, all patients will have extra blood samples set aside for a biobank.

At the end of the inclusion period, all patients sent to invasive coronary angiography (ICA) will be identified and included in the further analyses. As one center uses cTnT and one uses cTnI, patients will have either biomarker measured upon admission. The other cTn assay will be measured on all samples from the biobank, so every patient has at least one measurement of both cTnT and cTnI.