The investigators' objective is to compare a new strategy combining clinical history and NT-proBNP levels versus the usual care, consisting of early exercise testing, for decision making in patients presenting to the emergency department with acute chest pain, non-diagnostic electrocardiogram and normal troponin. The investigators hypothesised that the new strategy combining clinical risk score and NT-proBNP will reduce the number of hospitalisations without increasing the number of events during the follow-up.