An Update on the Prognosis of Patients With Atrial Fibrillation

Abstract

Atrial fibrillation (AF) is a highly prevalent and costly health problem, with an estimated incidence of 28 per 1000 person-years in the United States and an incremental national cost of $26 billion.1,2 The prevalence of AF is increasing; it is projected that, by 2050, AF will affect 6 to 12 million Americans.3,4 The growing burden of AF has far-reaching public health implications because of the association of AF with an increased risk of stroke, heart failure, and mortality.3,5,6 In recent years, the prognosis of patients with AF in certain at-risk subgroups, including those with heart failure, myocardial infarction, and chronic kidney disease, has been studied.7–10 In our brief review, we describe the most recently discovered AF-related prognostic factors,11 discuss some new prognostic algorithms for estimating the risk from AF and its complications,12 and highlight that additional efforts are needed to prevent AF-related cardiovascular morbidity and mortality. AF and Risk for Stroke Nonrheumatic AF is a major contributor to increased mortality rates5 and an independent risk factor predisposing to stroke.13,14 In community-dwelling individuals, the odds of developing a stroke is almost 5-fold higher in patients with known AF than in those who do not have clinically apparent AF.14 In the United States, the proportion of Americans aged ≥65 years is increasing and is estimated to reach 19.6% in 2030.15 These changing demographics suggest that rates of thromboembolic stroke may rise in the near future for several major reasons. The prevalence of AF increases dramatically with advancing age, and it is present in 9% to 18% of individuals by the age of 80 years.16 AF accounts for almost 1 in 4 strokes in patients aged ≥80 years.14 Furthermore, strokes from AF are associated with a 50% increased risk of serious disability and 60% increased risk of death at 3 months in comparison with strokes from other causes.17,18 The high degree of morbidity from strokes secondary to AF likely relates to 4 factors: (1) the thromboembolic nature of AF-related cerebrovascular events, (2) the association between AF and other cardiovascular diseases, (3) the predilection for strokes from AF to involve the anterior circulation or lead to multiple ischemic foci, and (4) the established associations between AF and proinflammatory and hypercoagulable states.19,20 Previous estimates associating AF with increased risk for stroke may not fully capture risk from AF, because AF is often asymptomatic and paroxysmal. Recent studies, in some cases using implantable electrocardiographic monitors, have emphasized that up to 21% of patients with stroke or transient ischemic attacks have undiagnosed AF.21 Although paroxysmal AF episodes lasting <30 seconds have traditionally been considered of little prognostic importance, a recent study showed that even high atrial rates of short duration are associated with higher risk for acute and chronic brain infarcts.22,23 AF may have an even stronger relation with stroke than was previously appreciated. Clearly, further research into the prognostic importance of brief episodes of AF in the community is needed to help guide stroke prevention in patients with short episodes.