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Incidence and Influence of Hospitalization for Recurrent Syncope and Its Effect on Short- and Long-Term All-Cause and Cardiovascular Mortality

https://doi.org/10.1016/j.amjcard.2014.02.035Get rights and content

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.

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Methods

In Denmark, all residents have a unique and permanent civil registration number that enables linkage on an individual level among nationwide administrative registries. We identified all patients aged 15 to 90 years who had a first-time diagnosis of syncope (International Classification of Diseases, tenth revision [ICD-10] discharge diagnosis R55.9) from all public hospitals and emergency departments in the period 2001 to 2009. The patients were censored at the end of follow-up (December 31,

Results

We identified a cohort of 70,819 patients with syncope discharged after admission (49%) or discharged directly from emergency department (51%) for first-time syncope. The mean age was 60 ± 20 years, 51% were men, and 38% had a cardiovascular co-morbidity at inclusion in the study (Table 1). During an average follow-up of 3.9 ± 2.6 years, 14,270 patients (20%) with syncope died from all causes, and 7,681 (54%) of these deaths were due to cardiovascular causes. The overall 1-year mortality for

Discussion

In this nationwide cohort of unselected patients hospitalized for first-syncope, we report the incidence of recurrence, the overall prognosis of these patients, and the influence of hospitalization for recurrent syncope on the risk of short- and long-term risk of all-cause death and cardiovascular death. To our knowledge, with the exception of specific cardiac conditions, no other study has investigated the influence of recurrent syncope on the risks of short- and long-term subsequent death.

Disclosures

Dr. Ruwald was supported by unrestricted grants 12-04-R90-A3806-22701 from The Danish Heart Foundation (Copenhagen, Denmark), R108-A104415 from The Lundbeck Foundation (Copenhagen, Denmark), 2012B018 from Helsefonden (Copenhagen, Denmark), Arvid Nilssons Fond (Copenhagen, Denmark), Snedkermester Sophus Jacobsen og Hustru Astrid Jacobsens Fond (Copenhagen, Denmark), and Else og Mogens Wedell-Wedellborgs Fond (Frederikssund, Denmark). The other authors have no conflict of interests related to

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