Lone atrial fibrillation: does it exist?

Abstract

The historical origin of the term "lone atrial fibrillation" (AF) predates by 60 years our current understanding of the pathophysiology of AF, the multitude of known etiologies for AF, and our ability to image and diagnose heart disease. The term was meant to indicate AF in patients for whom subsequent investigations could not demonstrate heart disease, but for many practitioners has become synonymous with "idiopathic AF." As the list of heart diseases has expanded and diagnostic techniques have improved, the prevalence of lone AF has fallen. The legacy of the intervening years is that definitions of lone AF in the literature are inconsistent so that studies of lone AF are not comparable. Guidelines provide a vague definition of lone AF but do not provide direction about how much or what kind of imaging and other testing are necessary to exclude heart disease. There has been an explosion in the understanding of the pathophysiology of AF in the last 20 years in particular. Nevertheless, there are no apparently unique mechanisms for AF in patients categorized as having lone AF. In addition, the term "lone AF" is not invariably useful in making treatment decisions, and other tools for doing so have been more thoroughly and carefully validated. It is, therefore, recommended that use of the term "lone AF" be avoided.

Keywords: idiopathic atrial fibrillation; lone atrial fibrillation; white paper.

Figure 1

The Demise of ‘Lone AF’. The pie charts illustrate the approximate proportions of AF considered to be ‘lone or idiopathic AF’, that is, AF in the absence of apparent heart disease in 1954 (upper left) and 2014 (lower right). In the intervening years, appreciation of a large and ever-expanding number of etiologic factors (center block arrow & Table 1) leading to an expanded definition of heart disease detectable with modern imaging and testing (center boxed list) and subdividing heart disease into traditional heart disease and new heart disease forms has dramatically reduced ‘lone or idiopathic AF’ from about 30% to about 3%.

Figure 2

Variation in the Definition of ‘Lone AF’. Survey of 125 studies reporting on ‘lone AF’ indicating the proportion of studies that excluded various risk factors for AF. The vertical axis is the percentage of studies and the bars represent the proportion that excluded a particular risk factor. COPD = chronic obstructive pulmonary disease.

Figure 3

Time-dependent Atrial Remodeling and Development of AF. A hypothetic construct over time indicating the interrelationships between time, risk factors for AF, atrial remodeling, detection of risk factors for atrial remodeling and progression from sinus rhythm through paroxysmal, persistent and permanent AF. ECV = electrical cardioversion, SR = sinus rhythm (Adapted from Cosio et al. Europace 2008, with permission).(104))