In patients with chest pain the diagnosis of a heart attack (myocardial infarction) is made where there is evidence of heart muscle damage using a blood test to measure the heart muscle protein troponin. A new a more sensitive troponin test may help us to identify patients with myocardial infarction more easily.

The investigators propose to evaluate whether use of a novel high-sensitivity troponin test to lower the threshold for diagnosis of myocardial infarction is appropriate. If increased sensitivity does not reduce specificity for the diagnosis, then this new test will improve patient outcome through better targeting of therapies for coronary heart disease. However, if increased sensitivity leads to poor specificity, then patients may be misdiagnosed and given inappropriate cardiac medications with potentially detrimental outcomes.

In ten secondary and tertiary care hospitals across Scotland, the investigators will undertake a stepped wedge cluster randomized controlled trial of the implementation of a novel high-sensitivity troponin test. The primary end-point will be the one-year rate of cardiovascular death or recurrent myocardial infarction. This will establish whether the introduction of this high-sensitivity troponin test into routine clinical practice is beneficial to patient management and outcomes.

A subset of patients will be asked to give consent for inclusion into a sub-study that will permit storage of blood samples and will require the completion of a survey during the index admission and after 6 and 12 months of follow up.

Inclusion criteria:

• Suspected acute coronary syndrome
• Troponin I measurement as part of routine clinical care

Exclusion criteria:

- None