External validation of a low HEAR score to identify emergency department chest pain patients at very low risk of major adverse cardiac events without troponin testing

Background The history, ECG, age, risk factor (HEAR) score has been proposed to identify patients at sufficiently low risk of acute coronary syndrome that they may not require troponin testing. The objective of this study was to externally validate a low HEAR score to identify emergency department (ED) patients with chest pain at very low risk of 30-day major adverse cardiac events (MACE). Methods This was a secondary analysis of a prospective cohort of patients requiring troponin testing to rule out myocardial infarction (MI) in a large urban ED. HEAR scores were calculated in two cohorts: (1) patients with no known history of coronary artery disease (CAD); and (2) all eligible patients. The proportion of patients classified as very low risk, sensitivity, specificity, predictive values and likelihood ratios at each cut-off were quantified for index acute myocardial infarction (AMI) and 30-day MACE at HEAR = 0 and HEAR <= 1 thresholds. Results Of the 1150 patients included in this study, 820 (71.3%) had no history of CAD, 97 (8.4%) had index AMI and 123 (10.7%) had 30-day MACE. In patients with no prior history of CAD, HEAR <= 1 identified 202 (24.6%) of patients as very low risk for 30-day MACE with 98.4% (95% CI 91.6-99.9%) sensitivity. Among all patients, HEAR <= 1 identified 202 (17.6%) patients as very low risk for 30-day MACE with 99.2% (95% CI 95.6-99.9%) sensitivity. Conclusions A HEAR score <= 1 can identify more than 17% of all patients as very low risk for index AMI and 30-day MACE and unlikely to benefit from troponin testing. Broad implementation of this strategy could lead to significant resource savings.