Cardiac findings and observation duration in patients with syncope in the emergency department: a cohort study

Early identification of cardiac syncope is critical because it is associated with adverse outcomes in the emergency department. However, the optimal observation duration remains unclear. In this study, we evaluated factors associated with ED observation time in patients with syncope, determined the timing of cardiac findings, and identified the clinical features that distinguish cardiac from neurally mediated or orthostatic syncope. A cohort study was conducted in the emergency department of an urban hospital, including 400 adult patients with syncope. Patients with transient loss of consciousness due to syncopal causes were excluded. The primary outcome was the presence and timing of cardiac findings (rhythm, structural cardiogenic, or both) during the observation period in the emergency department. Data were extracted from the electronic health records. Logistic regression was used to identify factors associated with cardiac syncope and time spent in the emergency department. Cumulative and incidence rate analyses of the time until a cardiac finding within 24 h were estimated using a time-to-event function. Cardiac syncope was associated with older age (OR: 1.04 per year; 95% CI: 1.02–1.07), prior pacemaker or ICD implantation (OR: 4.17; 95% CI: 1.50–11.6), absence of autonomic symptoms (OR: 0.16; 95% CI: 0.08–0.31), and abnormal electrocardiogram findings (OR: 6.84; 95% CI: 3.00–15.6), and higher rates of hospital admission (OR: 31.7; 95% CI: 14.1–71.3) and pacemaker implantation (OR: 63.0; 95% CI: 18.5–245). Cardiac findings were confirmed in 70.5% of patients initially classified as having cardiac syncope (OR: 33.0; 95% CI: 15.3–71.2). Most cardiac findings (70.9%) occurred within the first 12 h (incidence density: 1.04 vs. 0.54 per 100 patient-hours). The cumulative incidence increased from 12.5% at 12 h to 23.3% at 24 h, then slowed. Most cardiac findings were identified within the first 12 h of observation. These results support a selective strategy in which prolonged monitoring (≥ 12 h) may be reserved for patients with predefined clinical conditions, electrocardiographic markers, or concerns regarding underlying heart disease at initial assessment. Not applicable.