Angina is a common disabling condition that limits quality of life and shortens life expectancy. The diagnosis of angina is challenging and is currently made on the basis of a person’s symptoms and an exercise stress test. Unfortunately, exercise testing is insensitive creating considerable diagnostic uncertainty. We wish to assess whether the addition of a very sensitive blood test measuring a heart muscle protein (troponin) can improve our ability to diagnose angina. We hope this test can be used to identify those patients at risk of future heart attacks so that we can provide them with the best possible treatment.