Abstract 14997: Subclinical Device-Detected Atrial Fibrillation is Associated With a Higher Risk of Adverse Cardiovascular Outcomes to the Same Extent as Clinical Atrial Fibrillation

Abstract

Introduction: Atrial fibrillation (AF) is a known risk factor for adverse cardiovascular (CV) outcomes in patients with implantable cardioverter-defibrillators (ICDs). As the use of ICDs becomes more common, subclinical device-detected atrial fibrillation (SAF) is increasingly being identified. Studies have shown an association between SAF and increased risk of thromboembolic events. However, no study has compared the risk of adverse CV outcomes of SAF vs. clinical AF (CAF). Hypothesis: In patients with ICDs, SAF is associated with adverse CV outcomes to the same extent as CAF. Methods: We identified patients who had ICD implantation at the University of Minnesota Medical Center between Jan 1, 2003 and Dec 31, 2009. Baseline data on demographics, CV risk factors, diagnoses, and medications were collected. Follow-up was through Dec 31, 2012. Our primary outcome was a composite CV outcome (see table). CAF episodes were identified from clinical documents confirmed by ECGs. SAF episodes of any duration were identified from ICD interrogation reports. We fit a multivariable Cox proportional hazards model and used backwards stepwise selection to identify the most parsimonious model to predict the outcome (0.05 threshold). Results: We included 371 patients; 37 had incident or recurrent CAF; 88 had SAF. Median follow up was 490 days. The full model included age, sex, coronary artery disease, diabetes, ejection fraction, hypertension, and use of beta-blockers, anticoagulants, and ACE inhibitors. The table shows the most parsimonious model for prediction of the composite outcome. Conclusions: SAF and CAF were significantly associated with a greater than 11-fold and 9-fold increased risk of adverse CV outcomes, respectively. This study indicates that SAF is associated with increased risk of CV outcomes to the same extent as CAF. More research is needed to determine whether treatment of SAF (e.g., anticoagulation) will lead to improved outcomes in patients with ICDs.