Risk stratification of patients with syncope.

STUDY OBJECTIVE: To develop and validate a risk classification system for patients presenting to emergency departments with syncope.

METHODS: Two prospective studies were carried out at a large urban teaching hospital ED. One cohort of 252 patients with syncope who reported to the ED was used to develop the risk classification system; a second cohort of 374 patients with syncope was used to validate the system. Data from the patient's history, physical examination and ED ECG were used to identify predictors of arrhythmias or mortality within the first year. Arrhythmias were detected by cardiac monitoring or electrophysiologic studies. Logistic regression and Cox proportional hazards models were used to identify the important risk factors for the classification system. Performance of the system was measured by comparing the proportion of patients with arrhythmias or death at various levels of the risk and receiver operating characteristic curves.

RESULTS: Multivariate predictors of arrhythmia or 1-year mortality were an abnormal ED ECG (odds ratio [OR], 3.2; 95% confidence interval [CI], 1.6 to 6.4); history of ventricular arrhythmia (OR, 4.8; 95% CI, 1.7 to 13.9); history of congestive heart failure (OR, 3.2; 95% Cl, 1.3 to 8.1). Arrhythmias or death within 1 year occurred in 7.3% (derivation cohort) to 4.4% (validation cohort) of patients without any risk factors and in 80.4% (derivation) to 57.6% (validation) of patients with three or four risk factors.

CONCLUSION: Historical and ECG factors available at the time of presentation can be used to stratify risk of arrhythmias or mortality within 1 year in ED patients presenting with syncope.