Evaluation of the CHADS2 risk score on short- and long-term all-cause and cardiovascular mortality after syncope.

BACKGROUND: Syncope risk stratification is difficult and has not been implemented clinically. HYPOTHESIS: The CHADS2 score can be applied as a risk stratification tool for predicting mortality after an episode of syncope. METHODS: All patients discharged from emergency departments with a first-time diagnosis of syncope from 2001 to 2009 where identified from nationwide registers in Denmark and matched on sex and age with a control population. Risk of all-cause or cardiovascular death was analyzed by multivariable Cox models. RESULTS: A total of 37,705 patients were included. There were a total of 7761 deaths (21%), of which 52% were cardiovascular vs 27 862 (15%) deaths in the control population. The risk of cardiovascular death was significantly increased with increasing CHADS2 score (CHADS2 score: 1-2, hazard ratio [HR]: 9.11, 95% confidence interval [CI]: 8.25-10.07; CHADS2 score: 3-4, HR: 17.32, 95% CI: 15.42-19.47; CHADS2 score: 5-6, HR: 26.66, 95% CI: 21.40-33.21) relative to CHADS2 score of 0. A CHADS2 score of 0 was associated overall with very low event rates (15.1 deaths per 1000 person-years) but was associated with increased relative risk in the syncope population compared to controls. Syncope predicted 1-week, 1-year, and long-term mortality across CHADS2 scores compared to controls but did not reach significance in CHADS2 scores of 5 to 6. CONCLUSIONS: Increasing CHADS2 score significantly predicts mortality in patients discharged with a diagnosis of syncope, and a CHADS2 score of 0 was associated with a very low absolute mortality. Compared to controls, syncope was associated with increased short- and long-term mortality, particularly in the lower CHADS2 scores.