Cardiac implantable electronic devices and outcomes in heart failure patients with syncope

Abstract Funding Acknowledgements Type of funding sources: Private hospital(s). Main funding source(s): Mayo Clinic Background/Introduction Syncope is a common presentation in heart failure (HF) patients. However, the associations between syncope and prognosis in HF patients with the cardiac implantable electronic device (CIED) have not been demonstrated. It is unclear whether syncope increases all-cause mortality in HF patients with CIED. Purpose We aimed to examine the association between syncope and all-cause mortality in the largest cohort of HF with reduced ejection fraction (HFrEF), mid-ranged ejection fraction (HFmEF), and preserved ejection fraction (HFpEF) patients with and without CIED. Methods A retrospective cohort of patients with HF and syncope at our hospital between 2010 and 2015 were identified, and 1:1 propensity was matched with a control group of HF patients without syncope. A chart review was conducted. The multivariate Cox regression model was applied to estimate the association between syncope and the all-cause mortality endpoint. Results 3,449 HF patients were diagnosed with syncope (mean age, 72.8±14.5 years; 41.5% women), and the propensity-matched control HF patients without syncope (n=3,449) aged 72.8±14.3 years, and 42.5% women were selected. Cardiac implantable electronic devices were implanted more in HF patients with syncope (32.5% versus 13.7%, p<0.001). Implantable cardioverter defibrillators were implanted more in HF patients with syncope (15.6% versus 8.3%, p<0.001) as well as pacemakers (16.9% versus 7.5%, p<0.001) and cardiac resynchronization therapy devices (6.9% versus 4.8%, p=0.015). Among HF patients with CIED, syncope significantly increased the risk of all-cause mortality in HFrEF patients (hazard ratio [HR]=1.479, 95% confidence interval [CI]: 1.197-1.828, p<0.001) but not in HFpEF (HR=0.980, 95%CI: 0.793-1.210, p=0.849)(Figure 1). Syncope also tended to increase the risk of all-cause mortality in HFmEF patients with CIED but was not significant (HR=1.193, 95%CI: 0.762-1.865, p=0.762)(Figure 1). Among HF patients without CIED, syncope did not increase the risk of all-cause mortality in HFrEF (HR=0.923, 95%CI: 0.806-1.057, p=0.247), HFmEF (HR=1.074, 95%CI: 0.848-1.360, p=0.554), or HFpEF (HR=0.964, 95%CI: 0.883-1.052, p=0.406). Conclusions Syncope significantly increased the risk of all-cause mortality in HFrEF patients but not in HFmEF or HFpEF patients with CIED. The association of syncope and increased mortality in HFrEF patients with CIED suggests that syncope may be a marker and a factor of mortality and warrants further investigation.