Rapid rule out for suspected myocardial infarction: is the algorithm appropriate for all?

Aims Patients presenting to the emergency department (ED) with cardiac chest pain and high-sensitive troponin I (HsTnI) less than 5 ng/L have very good prognosis and low risk for major adverse cardiovascular events. The 2015 European Society of Cardiology (ESC) guidelines for non-ST-elevation myocardial infarction (MI)/acute coronary syndrome (ACS) suggests that patients with normal high-sensitive troponin, which are free of chest pain and have a global registry of acute coronary events (GRACE) score less than 140 are eligible for discharge from the hospital for outpatient workup. Our hypothesis suggests that not all patients with GRACE score under 140 should be discharged for ambulatory tests even with undetectable HsTnI as recommended in the guidelines. Methods and results Population-based retrospective cohort study in a large tertiary care centre. The study population included all patients discharged from the hospital between 1 February 2016 and 28 February 2019 following rule out of MI. During the study period, a total of 13 800 patients were discharged from the hospital after rule out of MI. Among them, 9236 (67%) had HsTnI below 5 ng/L. A total of 7705 patients (83%) met the criteria for low (n = 7162) or moderate (n = 543) GRACE risk score. Moderate-risk patients had significantly more adverse events than low-risk patients (4.6% vs. 2.1%, P < 0.001). They are in higher risk of death (0.5% vs. 0.1%, P = 0.042), revascularization (3.9% vs. 1.8%, P = 0.0047), and readmission due to ACS (1.1% vs. 0.4%, P= 0.031). Conclusion Patients presenting to the ED with chest pain and HsTnI less than 5 ng/L and GRACE score under 140 have 2-4% adverse event in 60 days. The differences between the groups suggest using rapid rule out algorithms for only low-risk patients with GRACE score under 73.