Patients suffering chest pain that is a definite heart attack (~20% of all presenters) now benefit from a more rapid assessment due to newer, recently implemented high sensitive tests that detect heart damage. However, most chest pain sufferers are not having a heart attack, with a sizeable group (~25%) instead suffering a repeated transient lack of blood flow to the heart, known as ischemia or angina. This group has much less certainty with respect to eventual diagnosis and the speed with which it is made due to the fact that there are no rapid blood tests to aid the clinician. We have discovered a protein in the blood that could help rapidly identify these ischemia patients. We will assess its ability to help the rapid diagnosis of ischemia/angina, how well it can predict outcomes in those patients and how much it may contribute to the onset of cardiac ischemia.