Currently when defining the upper limit of normal (ULN) or 99th percentile of a troponin assay manufacturer's use a healthy population traditionally aged 18-40. The 99th percentile value is the recommended value to use when diagnosing patients with an acute myocardial infarction. With the advent of the new highly sensitive troponin assays it has become clear that many patients have a troponin level above the 99th percentile when they have not suffered a myocardial infarction. We believe part of the problem with interpreting the the troponin values for patients is that the 99th percentile value which determines the ULN has been derived from population that is very different to the hospital population of patients. This study aims to demonstrate what the 99th percentile is for the population of people who use the hospital services who are traditionally older and have more comorbidities when compared to the population traditionally used to define the 99th percentile of a troponin assay.

An amendment was approved to follow-up patients' clinical outcomes at 1 year using NHS Digital data.

Inclusion Criteria:

• Adult patients (aged 18 years or older).
• Biochemistry blood sample already taken as part of routine clinical care.

Exclusion Criteria:

• Individuals aged less than 18 years old.
• No biochemistry blood sample taken as part of routine clinical care.
• Biochemistry samples requested by General Practitioner

All consecutive patients (inpatients or outpatients) who have had a biochemistry sample requested by a hospital clinician as part of their routine clinical care. A total of 20,000 consecutive patients will be recruited.