Chest pain and high-sensitivity troponin: What is the evidence?

The number of attendances and admissions of patients with chest pain to hospitals in England and Wales is increasing. Initial assessment may be unrewarding. Consequently, cardiac troponin has become the mainstay of investigation for non-ST-segment-elevation myocardial infarction and unstable angina, although only a small proportion of patients are eventually diagnosed as such. Current National Institute for Healthcare and Clinical Excellence guidance recommends measuring cardiac troponin levels on presentation and 10-12 h after onset of symptoms. A more effective diagnostic tool is needed. The aims are twofold: to increase accuracy of acute coronary syndrome diagnosis thus implementing the most appropriate management at an earlier stage while reducing costs and to provide a more rapid diagnosis to ease the anxieties of patients. Three key issues have been highlighted. The first is that many current studies do not have a 'normal/reference' population, making comparison between two studies difficult to interpret. Second, whether newer 'high-sensitivity' cardiac troponin tests can be used to rule out a myocardial infarction in a patient with chest pain is discussed. Third, whether a 'high-sensitivity' cardiac troponin has great enough specificity to differentiate between the number of other causes of raised troponin in a single test or whether serial testing is needed is assessed. A strategy for such serial testing is discussed. Finally, use of 'high-sensitivity' cardiac troponin in risk stratification of other disease processes is highlighted, which is likely to become common practice, changing the way we manage patients with, and without, chest pain.