Department of Cardiology, Gentofte Hospital, Hellerup, Denmark; Division of Cardiology, Heart Research Follow-up Program, University of Rochester Medical Center, Rochester, New York. Electronic address: firstname.lastname@example.org.
Recurrence of syncope is a common event, but the influence of recurrent syncope on the risk of death has not previously been investigated on a large scale. We examined the prognostic impact of recurrent syncope in a nationwide cohort of patients with syncope. All patients (n = 70,819) hospitalized from 2001 to 2009 in Denmark with a first-time diagnosis of syncope aged from 15 to 90 years were identified from national registries. Recurrence of syncope was incorporated as a time-dependent variable in multivariable-adjusted Cox models on the outcomes of 30-day, 1-year, and long-term all-cause mortality and cardiovascular death. During a mean follow-up of 3.9 ± 2.6 years, a total of 11,621 patients (16.4%) had at least 1 hospitalization for recurrent syncope, with a median time to recurrence of 251 days (33 to 364). A total of 14,270 patients died, and 3,204 deaths were preceded by a hospitalization for recurrent syncope. The long-term risk of all-cause death was significantly associated with recurrent syncope (hazard ratio 2.64, 95% confidence interval 2.54 to 2.75) compared with those with no recurrence. On 1-year mortality, recurrent syncope was associated with a 3.2-fold increase in risk and on 30-day mortality associated with a threefold increase. The increased mortality risk was consistent over age groups 15 to 39, 40 to 59, and 60 to 89 years, and a similar pattern of increase in both long-term and short-term risk of cardiovascular death was evident. In conclusion, recurrent syncope is independently associated with all-cause and cardiovascular mortality across all age groups exhibiting a high prognostic influence. Increased awareness on high short- and long-term risk of adverse events in subjects with recurrent syncope is warranted for future risk stratification.