Abstract 9575: Incidence of Subsequent Acute Coronary Syndrome in Patients with Atrial Fibrillation

Abstract

Background . Cardiovascular comorbidities associated with atrial fibrillation (AF) are also risk factors for acute coronary syndrome (ACS). We sought to determine the incidence of subsequent ACS in Medicare pts with newly diagnosed AF. Methods . The 5% Medicare database was used to identify pts (age 65+, no ESRD) with AF in 2006 without a prior diagnosis of ACS or AF. Medicare claims were used to identify patients hospitalized with ACS using ICD-9-CM codes for acute myocardial infarction (410) and unstable angina (411). The cumulative incidence of ACS and death was calculated during 3-year follow up using competing risk analysis and independent predictors of ACS were identified using a Cox proportional hazards model. Results . 18,445 Medicare pts were newly diagnosed with AF in 2006. The baseline characteristics of this population were: age 78 ± 7.8 yrs, hypertension (67%), CAD (33%), DM (26%), dyslipidemia (24%), CHF (21%), CVA/TIA (15%). 1392 (8%) patients from this cohort received an ACS diagnosis within 3 years (Figure). The rate of incident ACS was 11% in pts with prior CAD, CHF or DM. The rates of death at 3 years varied by age (49% for age ≥ 85, 26% for ages 75-84, 16% for ages 65-74). Independent risk factors for incident ACS included: female gender (HR 1.38, p==0.003), prior CAD (HR 1.78, p<0.0001), DM (HR 1.48, p <0.0001), CHF (HR 1.41, p <0.0001). Conclusion . Pts with a new diagnosis of AF had an 8% incidence of ACS within 3 years of the diagnosis of AF; this risk was higher in the presence of comorbid conditions. These data have important implications in chronically anti-coagulated AF pts, as the subsequent diagnosis of ACS will entail additional antiplatelet therapy and increased hemorrhagic risk. In elderly pts with AF, however, mortality is much more frequent than subsequent ACS.