External validation of the HEART, HEAR, and HET scores for prediction of major adverse cardiac events in adult patients with acute chest pain

BACKGROUND AND IMPORTANCE: In the cohort of patients presenting to the emergency department (ED) with acute chest pain differentiating between those at high risk of major adverse cardiac event (MACE), and those who can safely be discharged, remains a challenge. The history, ECG, age, risk factors, troponin (HEART) score, as well as several abridged versions [history, ECG, age, risk factors (HEAR), history, ECG, troponin (HET)]. are commonly used for this purpose. As with many clinical risk scores, they might be useful, but often lack proper validation. We aimed to externally validate the HEART, HEAR, and HET scores in the setting of a high-volume tertiary care ED in a healthcare system without gatekeeping functions and thus a low-risk population. We further aimed to compare the prognostic performance (discrimination and calibration) of the scores to each other. DESIGN: External validation study. SETTINGS AND PARTICIPANTS: On the basis of a-priori sample size calculations, we prospectively included consecutive adult patients presenting to the ED with acute chest pain. OUTCOME MEASURES AND ANALYSIS: We assessed overall model performance, discrimination, and calibration of all scores, analyzed reclassification from the HEART score and performed decision curve analysis. MAIN RESULTS: A total of 3273 patients were included, 383 (12%) suffered MACE within 30 days. Classification differed significantly between scores (HEART: 810; 25% low risk; HET: 55; 2%; HEAR: 195; 6%), as did overall performance (area under the curve: 0.85, 0.80, and 0.79, respectively; P < 0.001). HEART score misclassified 7/810 patients (0.9%; 95% confidence interval: 0.4-1.8%) with MACE as low risk, HET 2/55 (3.6%, 0.9-13.8%), and HEAR 0/195, whereas 2087 (72%), 2837 (98%), and 2695 (93%) patients without MACE were erroneously not classified as low risk. CONCLUSION: The abridged scores fell short of their results in derivation studies, identifying only very few low-risk patients, and showing inferior model performance compared with the original HEART score. Instead of developing new scores, existing scores should be recalibrated to local population characteristics, as needed.