Cardiovascular Journal of Africa: Vol 29 No 5 (September/October 2018)

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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 5, September/October 2018 268 AFRICA
Cardiovascular Topics
Clinical characteristics and outcome of lone atrial
fibrillation at a tertiary referral centre: the Groote Schuur
Hospital experience
Vinod Thomas, Simone Schulein, Robert N Scott Millar, Bongani M Mayosi
Abstract
Introduction: Atrial fibrillation (AF) is a relatively common
arrhythmia. When AF represents an electrophysiological
phenomenon in structurally normal hearts, it is termed
lone AF. This study was a retrospective, case-based analysis
of patients attending the Cardiac Clinic at Groote Schuur
Hospital (GSH) and describes the clinical characteristics and
outcomes of patients classified as having lone atrial fibrilla-
tion. To the best of our knowledge there are no such studies
reported from Africa.
Methods: This was a retrospective, descriptive study in which
289 medical records of patients with AF at the GSH Cardiac
Clinic were reviewed from 1992 to 2006. The clinical data were
interrogated to exclude identifiable causes of AF. Information
on clinical characteristics and outcomes were entered into a
data-entry form. Baseline descriptive statistics were expressed
as means and range for continuous variables, and counts with
percentages for categorical variables.
Results: Fifteen per cent (n = 42) of patients were identified
as having lone AF, with a mean follow-up time of 5.8 years.
Males comprised 57% (n = 24) and females 43% (n = 18). Fifty
per cent (n = 21) of the patients had paroxysmal AF, 29% (n
= 12) had persistent AF, and 12% (n = 5) progressed from
paroxysmal to permanent AF. Subsets of lone AF included
concomitant atrial flutter (17%) ( n = 7) and sick sinus
syndrome (21%) (n = 9). Complications were stroke (10%) (n
= 4), tachycardia-related cardiomyopathy (17%) (n = 7) and
bleeding complications on warfarin (11%) (n = 3).
Conclusion: Lone AF is not an uncommon arrhythmia, with
a preponderance in thin, middle-aged males. The symptoms
of lone AF can be debilitating. It has associated morbidity,
including tachycardia-related cardiomyopathy and thrombo-
embolism. Rate control and appropriate anticoagulation are
the cornerstones of patient management.
Keywords: lone atrial fibrillation, paroxysmal atrial fibrillation,
persistent atrial fibrillation, tachycardia-related cardiomyopathy,
stroke, anticoagulation, sick sinus syndrome, atrial flutter
Submitted 25/5/17, accepted 14/1/18
Cardiovasc J Afr 2018; 29: 268–272
DOI: 10.5830/CVJA-2018-005
Atrial fibrillation (AF) is a common and obstinate arrhythmia
that represents a growing epidemic, with significant health
consequences. It is often difficult to manage. The classical risk
factors for developing AF include hypertension, valvular heart
disease, thyroid disease and cardiomyopathies, including those
related to ischaemia.1 In some patients with AF, no underlying
cardiovascular pathology is present and the aetiology remains
unknown. This is known as lone atrial fibrillation. Lone AF
accounts for three to 20% of cases of atrial fibrillation.2,3. The
concept of lone AF is arbitrary and negative: the absence of
detectable structural heart disease.
There is increasing evidence that from a pathophysiological
point of view, the underlying mechanism of lone AF is different
from that of AF in the setting of underlying structural heart
disease. The latter is more substrate related, showing diseased
and dilated atria due to stretch and fibrosis. By contrast, lone AF
is probably more related to electrophysiological phenomena in
apparently structurally normal atria. This explains why patients
with lone AF have a normal life expectancy compared with
individuals without arrhythmia, a lower risk of heart failure,
and why paroxysmal lone AF has a lower risk of progression
to persistent or permanent AF.3-5 By contrast, AF in the
setting of underlying cardiac pathology usually progresses from
paroxysmal to persistent and/or permanent AF and is associated
with an increased incidence of stroke, heart failure and death.
Although lone AF follows a relatively benign course, it
adversely affects the quality of life and exercise capacity of
affected individuals.6 Regular follow up of lone AF patients is
essential, as in time, risk factors such as hypertension, diabetes
and ischaemic heart disease may develop, thereby altering the
prognosis.2,4,6 Recurrent paroxysms of AF in patients with lone
AF may also predispose to the formation of an atrial structural
substrate, which in time leads to left atrial dilatation. 7-9 This in
turn increases the risk of progression to persistent or permanent
AF, with its attendant increased risk of stroke and tachycardia-
The Cardiac Clinic, Department of Medicine, Groote
Schuur Hospital and University of Cape Town, Cape Town,
South Africa
Vinod Thomas, MB ChB (Wits), FCP (SA),
Simone Schulein MB ChB, FCA (SA)
Robert N Scott Millar MB ChB, FCP (SA)
Bongani M Mayosi MB ChB, FCP (SA), DPhil (Oxford)