Non traumatic chest pain is the second most common cause of attention at the Emergency Departments (ED). The objective is to compare the effectiveness of HEART risk score and the risk of having a Major Adverse Cardiovascular Event (MACE) during the following 6 weeks in 'Acute Non-traumatic Chest Pain' (ANTCP) patients of an ED in Lleida (Spain). The ANTCP patient cohort was defined using medical data from January 2015 to January 2016. A retrospective study was performed among 300 ANTCP patients. Diagnostic accuracy to predict MACE, HEART risk score effectiveness and patient risk stratification were analysed on the ANTCP Cohort. HEART risk score was conducted on ANTCP Cohort data and patients were stratified as low-risk (n = 116, 38.7%), moderate-risk (n = 164, 54.7%) and high-risk (n = 20, 6.7%); differently from the assessment performed by 'Current Emergency Department Guidelines' (CEDG) on the same patients: low risk and discharge (n = 56, 18.7%), medium risk and need of complementary tests (n = 137, 45.7%) and high risk and hospital admission (n = 107, 35.7%).The incidence of MACE was 2.5%, 20.7% and 100% in low, moderate and high-risk, respectively. Discrimination and accuracy indexes were moderate (AUC = 0.73, 95% confidence interval: 0.67-0.80). Clustering moderate-high risk groups by MACE incidence showed an 89.5% of sensitivity. Data obtained from this study suggests that HEART risk score stratified better 'acute non-traumatic chest pain' (ANTCP) patients in an Emergency Department (ED) compared with 'Current Emergency Department Guidelines' (CEDG) at the Hospital Universitari Arnau de Vilanova (HUAV). HEART score would reduce the number of subsequent consultations, unnecessary admissions and complementary tests.