Factfile: BHF resources
Atrial fibrillation (AF) is the commonest sustained arrhythmia.
You may find the following resourceshelpful to you and your patients:
AF increases the risk of heart failure and stroke, thereby impacting on long term survival.
Most patients will require oral medication to reduce thromboembolic risk.
A rhythm control strategy should be attempted in younger patients and in those with symptoms.
Many patients with AF can now be successfully treated with catheter ablation. Our research You will find information about the Introduction
Atrial fibrillation (AF) is the commonest sustained arrhythmia and affects almost a million people
in the UK. In 2000, the direct and indirect costs associated with the management of AF were £1.3 billion, which accounted for almost 2.5% of total NHS expenditure. As AF is more likely toaffect the elderly, its prevalence is likely to increase significantly in the next few decades. Causes of AF The majority of cases of AF are associated with hypertension, valvular disease or some other form of structural heart disease. Obesity is a well-recognized risk factor. However, in a significant minority no associated cardiac condition can be identified (‘Lone AF’).
In most patients AF originates from rapidly firing cells located at the junction of the pulmonaryveins with the left atrial musculature. This has led to the development of ablation proceduresdirected at these sites (see below).
Impact of AF Several large studies have shown that AF is associated with a doubling of the mortality risk, and that a diagnosis of AF may be associated with a shortening of the life span by around 5 years for men and 8 years for women.2 There are 3 main reasons for this:
AF increases the risk of stroke 5-fold – the strokes associated with AF are also more likely to be disabling and fatal.
AF results in loss of atrial contraction and decreases cardiac output by almost a quarter.
The fast and erratic heart rates in AF can result in deterioration in LV function over time. Due to these latter two factors, AF is associated with a greater than 3 fold increased risk of heart failure. Diagnosis Patients may present with either paroxysmal AF or with persistent AF.
Patients with paroxysmal AF usually present with episodic palpitations lasting minutes to hours. Obtaining ECG diagnosis can be difficult and requires a high index of suspicion. Attempts shouldbe made to record an ECG at the time of symptoms, and ECG event loop recorders have a higherdiagnostic yield compared to Holter monitoring. In difficult cases, implantable Loop recordersmay be required.
Persistent AF is the more advanced stage of the disease, and is defined as continuous AF that is sustained beyond seven days. This is sometimes detected incidentally as irregular pulsemeasurements. A simple ECG should be diagnostic in these cases. Management strategies for patients with AF There are two broad approaches to the treatment of atrial fibrillation:
Rhythm Control: using strategies to restore and maintain sinus rhythm. These have historicallyincluded cardioversion and/or treatment with antiarrhythmic drugs. Since 2000, catheterablation has also been increasingly used for this purpose.
Rate Control: this allows atrial fibrillation to persist, but the heart rate is controlled with drugs. Factfile:
Three large prospective randomized trials (AFFIRM, RACE, STAF) compared these two
References 1. Stewart S, Murphy N,Walker A,
treatment strategies. They studied mostly elderly patients with persistent or permanent
AF with minimal symptoms, and showed broadly equal outcomes in the two management
strategies. These studies had several limitations. The antiarrhythmic drugs used to try and
analysis of atrial fibrillation in the UK. Heart. 2004 Mar;90(3):286-92
maintain normal rhythm proved ineffective in more than half the cases. This limited efficacysignificantly jeopardized the rhythm control groups in comparative analysis. Antiarrhythmic
2. 2. mpact of atrial fibrillation on the
drug therapy was associated with significantly increased mortality. It has since been proven
risk of death: The Framingham heartstudy. Benjamin EA, Wolf PA, D’
that the drugs used can increase the risk of sudden cardiac death by prolonging the QT
interval and predisposing to ventricular arrhythmias. More patients in the rhythm control
groups had interruptions in anti-coagulation treatment. These studies predated the advent of catheter ablation.
3. 3. Cardioversion of atrial fibrillation:
the use of antiarrhythmic drugs. Schilling RJ. Heart 2010:96:333-338
Many physicians misinterpreted the headline results of these studies that atrial fibrillation and sinus rhythm are associated with equal survival rates. To the contrary, post-hoc analysis
of study data showed that presence of normal rhythm was strongly associated with a better
survival rate. As such, current scientific opinion is now agreeing on the fact that rhythm
control to normal sinus rhythm should be the preferred goal for most patients, especially
for those with limiting symptoms and in younger patients. Rhythm control Antiarrhythmic drugs
originating in the pulmonary veins. Haissaguerre M, Jais P, Shah D et al. N
Flecainide and Sotalol are effective but are contraindicated in patients with ischaemic heart
disease and those with impaired ventricular function. The most effective agent is Amiodaronebut this is associated with significant side effects and requires regular monitoring of both liver
atrial fibrillation. The task force for the
and thyroid function. Dronedarone has modest efficacy in paroxysmal AF, but has been
associated with safety concerns when used for non-paroxysmal AF.
the European Society of Cardiology. European Heart Journal
This is the most common mode of trying to achieve rhythm control and works acutely in
>90% patients, especially if patients are started on anti-arrhythmic drug therapy beforehand.
However, AF recurs over time in many patients, and so this treatment should not be assumed
of catheter ablation for human atrialfibrillation. Cappato R, Calkins H, Chen
to be definitive. Consideration should be given to referring patients for ablation therapy
rather than performing electrical cardioversion repeatedly. Ablation therapy The discovery of the pulmonary veins as the site for initiation of AF has led to the development of curative catheter-based procedures. These involve the delivery of radiofrequency energy with an aim to isolate the pulmonary veins electrically from the left atrium. There has been an evolution of such techniques since 1997 and currently the expected success rate is around 80% in experienced hands. This can often only be achieved with the use of multiple procedures and at a 3-4% potential risk of procedural complications such as groin complications, cardiac tamponade, and stroke.
A number of studies have shown that catheter ablation is superior to antiarrhythmic drugs in maintaining sinus rhythm. Latest clinical guidelines support the use of ablation therapy as first line treatment for patients with lone paroxysmal AF and as second line treatment for persistent AF. The success rates with ablation are highest in patients with paroxysmal AF, and in persistent AF of less than 12 months duration. Ablation is less likely to be successful in the presence of advanced structural heart disease, or in long standing persistent AF. There
Factfile is an information resource produced
has been an exponential increase in number of ablation procedures for AF worldwide, and
by the British Heart Foundation for GPs based
this trend is likely to gather even more pace in the coming years.
on up to date clinical evidence and expertopinion. As a digest of many data sources, it is necessarily the culmination of assessments
Rate control treatment
made by the BHF’s medical professionals and
Rate control drugs include: Digoxin, beta-blockers or Calcium Channel blockers such
should not be taken as a definitive statementof correct clinical practice in any given
as Verapamil to get a resting heart rate of less than 100-110 bpm. Often a combination
situation. Consequently, the BHF is not able
of these drugs is needed for satisfactory rate control. Ablation of the AV node is an alternative
to give any warranties in relation to particularclinical decisions taken or courses of
that is very effective in abolishing/reducing symptoms. It is, however, a palliative procedure,
requires pacemaker implantation and continued anticoagulation as the atria continue
the information contained in the Factfiles. British Heart Foundation Greater London House 180 Hampstead Road Anticoagulation in patients with AF
The most important decision to be made with a patient in AF is whether or not they should
be anticoagulated, and if so with which drug(s). This will be covered in detail in the next
registered charity in England and Wales(225971) and in Scotland (SC039426).
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