Lone Atrial Fibrillation -- An Overview
Similar to AF with an underlying disease, 'lone' AF is more frequent in males (male-to-female ratio of 3–4:1). Male preponderance is more striking in sporadic 'lone' AF compared with familial AF, possibly because of a concealed X-linked recessive AF in males with negative family history and apparently sporadic AF, whose mothers and sisters might be the healthy carriers. However, familial and sporadic 'lone' AF are clinically indistinguishable.
Aging is closely related with the risk of incident AF. Overall, the prevalence of AF in individuals younger than 60 years is < 1%, whilst ~10% of those ≥ 80 have AF. However, the true prevalence of 'lone' AF is unknown, ranging between 1.6% and 30% of all AF cases in the published reports which used variable definitions of 'lone' AF with respect to the age limit, left atrial size and associated hypertension.
In general, data on the natural history and prognosis of 'lone' AF are sparse. The clinical perception of 'lone' AF mostly stems from the results of a relatively small number of observational studies and a post hoc analysis from one randomised trial, which compared rate vs. rhythm control in patients with non-valvular AF ( Table 2 ). These studies have certain limitations, including the small cohorts wherein some patients even were not truly 'lone' AF because of older age or hypertension. The studies yielded conflicting results, but most of them suggested that 'lone' AF is a benign disorder with outcomes comparable to the general adult population ( Table 2 ).
The largest of the 'lone' AF studies, with 346 carefully characterised newly diagnosed 'lone' AF patients and a 12-year follow-up, demonstrated that these patients do have a favourable prognosis as long as they have truly 'lone' arrhythmia. However, with aging and/or the occurrence of cardiovascular comorbidities in such patients, the risk of development of AF-related complications (e.g., thromboembolic events or HF) increases. A recent study suggested that 'lone' AF patients develop cardiovascular disease more often, at younger age and with a more severe disease profile compared with healthy controls in sinus rhythm. However, the study was rather small (only 41 'lone' AF patients) and the findings could be just a play of chance. Another study observed that as many as 44% of patients originally thought to have 'lone' AF may actually have occult hypertension. Taken together, these data suggest that 'lone' AF patients should have a regular clinical follow-up dedicated to the primary and secondary prevention of cardiovascular disease and AF-related complications.
Paroxysmal (i.e., self-terminating) 'lone' AF has been suggested to implicate a better prognosis in terms of thromboembolic events and mortality, as compared to chronic 'lone' arrhythmia. Indeed, majority of 'lone' AF patients present with paroxysmal arrhythmia and have a relatively low rate of progression to permanent AF over a long-term follow-up. In the Belgrade AF study, for example, < 10% of patients initially had a permanent arrhythmia. However, the progression from paroxysmal to chronic AF subsequently occurred in 27% of patients (at 11.9 ± 7.5 years following the AF diagnosis) and was an independent marker for adverse cardiovascular events.
In the original description of 'lone' AF, the authors had emphasised that there was no increase in the left atrial size during follow-up (at least as assessed using chest radiography). More recently, it has been shown that 'lone' AF patients with increased left atrial volume (>32 ml/m), either at diagnosis or during the follow-up, subsequently experienced adverse cardiovascular events including stroke.
Prevalence, Clinical Course and Long-term Outcomes of 'Lone' Af
Similar to AF with an underlying disease, 'lone' AF is more frequent in males (male-to-female ratio of 3–4:1). Male preponderance is more striking in sporadic 'lone' AF compared with familial AF, possibly because of a concealed X-linked recessive AF in males with negative family history and apparently sporadic AF, whose mothers and sisters might be the healthy carriers. However, familial and sporadic 'lone' AF are clinically indistinguishable.
Aging is closely related with the risk of incident AF. Overall, the prevalence of AF in individuals younger than 60 years is < 1%, whilst ~10% of those ≥ 80 have AF. However, the true prevalence of 'lone' AF is unknown, ranging between 1.6% and 30% of all AF cases in the published reports which used variable definitions of 'lone' AF with respect to the age limit, left atrial size and associated hypertension.
In general, data on the natural history and prognosis of 'lone' AF are sparse. The clinical perception of 'lone' AF mostly stems from the results of a relatively small number of observational studies and a post hoc analysis from one randomised trial, which compared rate vs. rhythm control in patients with non-valvular AF ( Table 2 ). These studies have certain limitations, including the small cohorts wherein some patients even were not truly 'lone' AF because of older age or hypertension. The studies yielded conflicting results, but most of them suggested that 'lone' AF is a benign disorder with outcomes comparable to the general adult population ( Table 2 ).
The largest of the 'lone' AF studies, with 346 carefully characterised newly diagnosed 'lone' AF patients and a 12-year follow-up, demonstrated that these patients do have a favourable prognosis as long as they have truly 'lone' arrhythmia. However, with aging and/or the occurrence of cardiovascular comorbidities in such patients, the risk of development of AF-related complications (e.g., thromboembolic events or HF) increases. A recent study suggested that 'lone' AF patients develop cardiovascular disease more often, at younger age and with a more severe disease profile compared with healthy controls in sinus rhythm. However, the study was rather small (only 41 'lone' AF patients) and the findings could be just a play of chance. Another study observed that as many as 44% of patients originally thought to have 'lone' AF may actually have occult hypertension. Taken together, these data suggest that 'lone' AF patients should have a regular clinical follow-up dedicated to the primary and secondary prevention of cardiovascular disease and AF-related complications.
Paroxysmal (i.e., self-terminating) 'lone' AF has been suggested to implicate a better prognosis in terms of thromboembolic events and mortality, as compared to chronic 'lone' arrhythmia. Indeed, majority of 'lone' AF patients present with paroxysmal arrhythmia and have a relatively low rate of progression to permanent AF over a long-term follow-up. In the Belgrade AF study, for example, < 10% of patients initially had a permanent arrhythmia. However, the progression from paroxysmal to chronic AF subsequently occurred in 27% of patients (at 11.9 ± 7.5 years following the AF diagnosis) and was an independent marker for adverse cardiovascular events.
In the original description of 'lone' AF, the authors had emphasised that there was no increase in the left atrial size during follow-up (at least as assessed using chest radiography). More recently, it has been shown that 'lone' AF patients with increased left atrial volume (>32 ml/m), either at diagnosis or during the follow-up, subsequently experienced adverse cardiovascular events including stroke.
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