Edward H. Suh, MD*; Dana L. Sacco, MD, MPH; Carolyn Winskill, MS; John DeAngelis, MD; Daniel Nishijima, MD, MAS;
Jonathan Schimmel, MD; Alan Storrow, MD; Venkatesh Thiruganasambandamoorthy, MBBS, MSc; Robert E. Weiss, MS;
Nancy Wood, MPA, MS; Marc A. Probst, MD, MS
ABSTRACT 
Study objective: Previous research suggests that the short-term incidence of adverse events is similar in emergency
department (ED) patients with presyncope and syncope. However, admission rates for presyncope are lower, which could imply
clinicians underestimate its risk. We sought to compare physician risk estimates and the 30-day rate of serious cardiac
outcomes between patients with syncope and presyncope.
Methods: We conducted a secondary analysis of a prospective, observational, multicenter study of patients aged ≥40 years
presenting to ED with presyncope or syncope. Patients with serious ED diagnoses were excluded. Descriptive statistics and
multivariable regression analyses were used to compare the physician-estimated risk, ED disposition, and 30-day rate of
adverse outcomes.
Results: Of the 1,263 patients analyzed, 721 (57%) had syncope and 542 (43%) had presyncope. Baseline characteristics were
similar between groups. At 30 days, 34 (4.7%) syncope patients and 28 (5.2%) presyncope patients experienced a serious
cardiac outcome; logistic regression showed no difference in the odds (odds ratio 1.13; 95% confidence interval 0.66 to 1.79) of
serious cardiac outcomes between syncope and presyncope patients. The mean physician-estimated risk of serious cardiac
outcomes was 7.6% in syncope, versus 5.3% in presyncope (risk difference 2.3% [0.89%, 3.7%]); this difference remained
significant after adjustment for clinical characteristics. Admission rate was lower in presyncope, 38.2% versus 49.5% (risk
difference 11.3% [1.2%, 21.5%]).
Conclusion: Patients with unexplained presyncope and syncope had similar rates of 30-day serious cardiac outcomes after ED
visit. Patients with presyncope were less likely to be admitted and had a lower mean physician-estimated risk of adverse
outcomes. [Ann Emerg Med. 2025;■:1-10
