Epidemiology of syncope in hospitalized patients

Abstract

Objective: To describe the etiologies of syncope in hospitalized patients and determine the factors that influence survival after discharge.

Design: Observational retrospective cohort.

Setting: Department of Veterans Affairs hospital, group-model HMO, and Medicare population in Oregon.

Patients: Hospitalized individuals (n = 1,516; mean age +/- SD, 73.0 +/- 13.4 years) with an admission or discharge diagnosis of syncope (ICD-9-CM 780.2) during 1992, 1993, or 1994.

Measurements and main results: During a median hospital stay of 3 days, most individuals received an electrocardiogram (97%) and prolonged electrocardiographic monitoring (90%), but few underwent electrophysiology testing (2%) or tilt-table testing (0. 7%). The treating clinicians identified cardiovascular causes of syncope in 19% of individuals and noncardiovascular causes in 40%. The remaining 42% of individuals were discharged with unexplained syncope. Complete heart block (2.4%) and ventricular tachycardia (2. 3%) were rarely identified as the cause of syncope. Pacemakers were implanted in 28% of the patients with cardiovascular syncope and 0. 4% of the others. No patient received an implantable defibrillator. All-cause mortality +/- SE was 1.1% +/- 0.3% during the admission, 13% +/- 1% at 1 year, and 41% +/- 2% at 4 years. The adjusted relative risk (RR) of dying for individuals with cardiovascular syncope (RR 1.18; 95% confidence interval [CI] 0.92, 1.50) did not differ from that for unexplained syncope (RR 1.0) and noncardiovascular syncope (RR 0.94; 95% CI 0.77, 1.16).

Conclusions: Among these elderly patients hospitalized with syncope, noncardiovascular causes were twice as common as cardiovascular causes. Because survival was not related to the cause of syncope, clinicians cannot be reassured that hospitalized elderly patients with noncardiovascular and unexplained syncope will have excellent outcomes.

FIGURE 1

Influence of age on survival after syncope admission (n = 1,516). Survival after an admission for syncope is profoundly affected by age.

FIGURE 2

Influence of Charlson Comorbidity Index on survival after syncope admission (n = 1,516). A marked difference in survival is seen for patients with higher Charlson indices. These differences continue for the entire period of follow-up.

FIGURE 3

Unadjusted survival after syncope: influence of the etiology of syncope (n = 1,516). Unadjusted Kaplan-Meier survival curves show no differences in survival between the causes of syncope.

Figure 4

Age-stratified survival among patients with different etiologies of syncope. (A) Individuals younger than 55 years; (B) individuals between 55 and 64 years of age; (C) individuals between 65 and 74 years of age; (D) individuals between 75 and 84 years of age; and (E) individuals 85 years of age or older. Survival in each age stratum does not differ among individuals with different etiologies of syncope; p values from log-rank tests are adjusted for secondary comparisons. Cardiovascular syncope, dotted line; unexplained syncope, solid black line; noncardiovascular syncope, gray line. CV denotes cardiovascular.

Figure 4

Age-stratified survival among patients with different etiologies of syncope. (A) Individuals younger than 55 years; (B) individuals between 55 and 64 years of age; (C) individuals between 65 and 74 years of age; (D) individuals between 75 and 84 years of age; and (E) individuals 85 years of age or older. Survival in each age stratum does not differ among individuals with different etiologies of syncope; p values from log-rank tests are adjusted for secondary comparisons. Cardiovascular syncope, dotted line; unexplained syncope, solid black line; noncardiovascular syncope, gray line. CV denotes cardiovascular.