Is syncope a risk factor for poor outcomes? Comparison of patients with and without syncope

To determine whether syncope, independent of underlying comorbidities, is associated with increased mortality or other cardiovascular outcomes.

A prospective cohort study of patients with syncope and a group of patients without syncope matched with respect to age, gender, site of care (inpatient/ outpatient) and a cardiac disease index at an urban university medical center. Overall mortality, cardiac mortality, cardiovascular outcomes, and occurrence of syncope within 1 year of study enrollment were compared between the groups with Kaplan-Meier rates and Mantel-Cox statistics.

The characteristics of 470 patients with syncope and the matched patients without syncope were similar except that the patients without syncope had more cardiac diseases than those with syncope (P = 0.002). Patients with and without syncope had similar rates of 1-year overall mortality (9% versus 11%, P = 0.29) and cardiac mortality (3% versus 6%, P = 0.08). In multivariate analyses, syncope was not a significant predictor of overall or cardiac mortality, but male gender, age > 55 years, and congestive heart failure were. One-year rates for other cardiovascular outcomes (myocardial infarction, congestive heart failure, cardiac arrest with survival, and cerebrovascular events) in patients with syncope were similar to those in patients without syncope (P > or = 0.2 for all comparisons). Patients with syncope had a 20.2% recurrence rate in 1 year as compared with a 2.1% rate for new syncope in patients without prior syncope (P < 0.00001).

Syncope itself is not a risk factor for increased overall and cardiac mortality or cardiovascular events. Underlying heart diseases are risk factors for mortality regardless of whether the patient has syncope or not. The major focus of the evaluation of patients with syncope should be to identify and treat underlying heart diseases.