SA JOURNAL OF DIABETES & VASCULAR DISEASE
REVIEW
VOLUME 7 NUMBER 2 • JUNE 2010
57
arising from pulmonary veins) and mechanisms of perpetuation (
eg
re-entry or circus movement of electrical waves in the atria). It is
no surprise that AF is highly heterogeneous and that attempting to
combat it is highly challenging.
Management
Optimal management of AF requires:
Recognition of AF (symptomatic or asymptomatic) and treatment
•
of underlying conditions
Assessment and optimisation of thromboembolic risk
•
Treatment of the heart rate and/or rhythm.
•
Recognition of AF
Clinical history and physical examination
AF may be suspected in a patient because of symptoms including
palpitation, breathlessness, exercise intolerance, or dizziness, or
simply because of the opportunistic finding of an irregular pulse.
Indeed, the diagnosis may be easily missed unless the pulse is
taken manually. The finding of an irregular pulse should prompt
confirmation of the diagnosis by 12-lead ECG. Diagnosis may require
ambulatory ECG recordings in cases of intermittent symptoms.
Identification of precipitating causes
When AF occurs secondary to acute reversible causes such as
hyperthyroidism, acute peri/myocarditis, alcohol, respiratory tract
infections, acute myocardial infarction, and cardiac surgery, it
usually responds to treatment of the underlying condition.
It is important to evaluate for other medical conditions,
particularly underlying structural heart disease. The majority of
AF is associated with the presence of underlying co-morbidities –
many of which can contribute to its pathophysiology, for example,
hypertension, coronary artery disease, valvular (typically mitral but
also aortic) disease, heart failure of any cause, diabetes mellitus,
alcohol excess, and thyroid dysfunction. However, these are
common conditions in the general population that simply increase
the risk for developing AF.
Some patients prone to AF, particularly if young and paroxysmal,
have no apparent causative factor after thorough investigation. AF
in these patients is termed ‘lone’,
10
but its treatment remains the
same.
Investigations
An ECG is useful in confirming the diagnosis while at the same time
looking for evidence of left ventricular hypertrophy (hypertension,
hypertrophic cardiomyopathy), previous myocardial infarction, and
pre-excitation (a component of Wolff-Parkinson-White syndrome),
even during sinus rhythm.
Baseline blood tests should be performed including thyroid
function, blood counts, and renal/liver function. This is both to rule
out an underlying cause and to guide appropriate therapy.
Do I need to refer for an echocardiogram?
While the European Society of Cardiology recommends an
echocardiogram as part of baseline evaluation in all patients, NICE
guidelines, which include analysis of cost effectiveness, recommend
that transthoracic echo-cardiography (TTE) be performed in patients
with AF:
for whom a baseline echocardiogram is important for long-
•
term management, such as younger patients
for whom a rhythm-control strategy that includes cardioversion
•
(electrical or pharmacological) is being considered
in whom there is a high risk or a suspicion of underlying
•
structural/functional heart disease (such as heart failure or
heart murmur) that influences their subsequent management
(for example, choice of anti-arrhythmic drug)
in whom refinement of clinical risk stratification for
•
antithrombotic therapy is needed.
Characterisation of pattern of AF
It is useful to identify the pattern of AF in a given patient, because
this will affect the treatment strategy chosen.
First detected AF episode.
•
Recurrent AF, which may be paroxysmal or persistent:
Paroxysmal – episodes which spontaneously terminate,
•
<
7 days
(usually
<
48 hours)
Persistent – when sustained
•
>
7 days
Permanent – long-standing AF, usually
•
>
1 year, or when
cardioversion has failed or not been attempted. In the modern
era of catheter ablation, this may be termed ‘
long-standing
persistent
’ as even permanent AF can be successfully treated
and sinus rhythm restored in many patients.
Symptomatic status
A significant proportion of patients, particularly the elderly, may
not be aware of the arrhythmia, or disregard their mild symptoms
as a feature of ageing. Evidence would suggest it is reasonable
to manage these patients with anticoagulation and rate-control as
needed.
However, many patients present with symptoms due at least in
part to AF. A scoring system (CCS-SAF), akin to that used in angina
and heart failure, has been proposed to help categorise symptom
severity in AF patients,
11
which could be useful both in deciding on
management strategies and assessment of its efficacy.
It is the degree of symptoms that, in general, will govern the
decision regarding referral for specialist care. For those with newly-
diagnosed AF, the decision can often wait until the patient has
been given a trial of appropriate pharmacological therapy (see
below), unless acute hospital admission is warranted.
Key messages
Atrial fibrillation (AF) is the commonest sustained cardiac
•
arrhythmia
It is a leading cause of stroke, and suitable thromboprophylaxis
•
should be considered in all patients
Treatment should be tailored to the individual
•
In asymptomatic individuals, rate control may suffice
•
In symptomatic patients, particularly those with paroxysmal
•
AF, a rhythm-control strategy is generally recommended
Catheter ablation is an effective therapy for symptomatic
•
patients who fail or cannot tolerate antiarrhythmic drugs
