Thiruganasambandamoorthy V, et al. - In this prospective cohort study including adult (≥ 16 years) patients presenting within 24-hours of syncope at 6 Emergency Departments (EDs), researchers focused on the incidence and time to arrhythmia occurrence to inform decisions regarding duration of monitoring based on ED risk-stratification. They excluded patients with an obvious serious condition on ED presentation and those with missing Canadian Syncope Risk Score (CSRS) predictors. Participants were followed for 30-days. Of 5,581 patients (mean age 53.4 years, 54.5% females, 11.6% hospitalized), serious outcomes were seen in 417 (7.5%) patients of which 207 (3.7%) were arrhythmic (161 arrhythmias, 30 cardiac device implantations, 16 unexplained death). Findings revealed that it was common to detect serious underlying arrhythmia within the first 2-hours of ED arrival in CSRS low-risk patients and within 6-hours for CSRS medium- and high-risk patients. For selected medium-risk patients and all high-risk patients discharged from the hospital, considering outpatient cardiac rhythm monitoring for 15-days was recommended in this study.