This study sought to examine the risk of major cardiac adverse events and death in a nationwide cohort of patients without previous comorbidity admitted for syncope.
Syncope is a common clinical event, but knowledge of prognosis is not fully elucidated in healthy individuals.
Patients without previous comorbidity admitted for syncope in Denmark from 2001 to 2009 were identified in nationwide administrative registries and matched by sex and age with 5 control subjects from the Danish population. The risk of death or recurrent syncope, implantation of pacemaker or implantable cardioverter-defibrillator, and cardiovascular hospitalization were analyzed with multivariable Cox proportional hazard models.
We identified 37,017 patients with a first-time diagnosis of syncope and 185,085 control subjects; their median age was 47 years (interquartile range, 32 to 63 years) and 47% were male. A total of 3,023 (8.2%) and 14,251 (7.1%) deaths occurred in the syncope and the control population, respectively, yielding an event rate of 14.3 per 1,000 person-years (PY) in the syncope population. Multivariable Cox regression analysis demonstrated a significantly increased risk of all-cause mortality (hazard ratio [HR]: 1.06; 95% confidence interval [CI]: 1.02 to 1.10), cardiovascular hospitalization event rate of 26.5 per 1,000 PY (HR: 1.74; 95% CI: 1.68 to 1.80), recurrent syncope event rate of 45.1 per 1,000, stroke event rate of 6.8 per 1,000 PY (HR: 1.35; 95% CI: 1.27 to 1.44), and pacemaker or implantable cardioverter-defibrillator event rate of 4.2 per 1,000 PY (HR: 5.52; 95% CI: 4.67 to 5.73; p < 0.0001).
The first admission for syncope among healthy individuals significantly predicts the risk of all-cause mortality, stroke, cardiovascular hospitalization, device implantation, and recurrent syncope.