HEART FAILURE OUTCOMES AND PREDICTORS OF SUBCLINICAL ATRIAL FIBRILLATION PROGRESSION

Abstract

Long-term monitoring with implanted cardiac devices can detect asymptomatic, subclinical atrial fibrillation (SCAF). We hypothesized that progression from shorter to longer SCAF episodes would be associated with a higher risk of congestive heart failure (CHF), one of the leading causes of AF-related morbidity and mortality. Subjects in the Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the Atrial Fibrillation Reduction Atrial Pacing Trial (ASSERT) were ≥65 years, had a history of hypertension, no known prior clinical AF, and had an implanted pacemaker or defibrillator. Among participants whose longest episode of SCAF was between >6 minutes and 24 hours during the first 12 months after enrollment (N=415), we evaluated the relationship between subsequent development of SCAF >24 hours or clinical AF and CHF hospitalization using time-dependent Cox proportional-hazards models. Over a mean follow-up of 2 years, 65 patients (15.7%) progressed to SCAF >24 hours or clinical AF (incidence rate 8.8%/year). The rate of CHF hospitalization among patients with versus without SCAF progression was 8.9 and 2.5%/year, respectively. SCAF progression was independently associated with CHF hospitalization in multivariable models (HR 4.58, 95%-CI 1.64 – 12.8, p=0.004). Similar results were observed after exclusion of patients with prior history of CHF (7.06, 95%-CI 1.82-27.3, p=0.005); when examining progression in patients with SCAF between >6 minutes and 12 hours in the first year (HR 7.73, 95%-CI 2.52-23.8, p < 0.001); and when defining SCAF progression as >24 hours only (HR 3.68, 95%-CI 1.27-10.7, p=0.016). Older age (HR 1.59, 95%-CI 1.05-2.39 per 10 year increment), increasing body mass index (HR 1.83, 95%-CI 1.14-2.94 per 10 kg/m2 increment) and longer SCAF duration within the first year of enrollment (HR 1.13, 95%-CI 1.09-1.17 per 1 hour increment) were independent predictors of SCAF progression. In this prospective cohort of older, hypertensive patients with an implanted pacemaker or defibrillator, SCAF progression was a strong and independent predictor of CHF hospitalization.