top ten tips in atrial fibrillation

 

What is the impact of AF?

1.2 million patients in the UK have atrial fibrillation, (AF), AND the incidence is rising at 5% per annum. AF consumes 1% of the NHS annual budget, (>£1bn). AF is associated with more 575,000 UK hospital admissions, causes another 95,000 admissions per annum. Large studies such as the Framingham Study show that AF roughly doubles the risk of death in both sexes, independent of age group.  Health care costs of AF are 9- to 23-fold greater than in those without.  In the UK, only about 20% of patients with established AF, eligible for warfarin are being treated with it.  One-in-3 stroke patients is admitted in AF.  Elderly patients, in particular, may have asymptomatic AF, and have a high stroke-risk.


Atrial flutter.

Atrial flutter is allied to AF, has a similar stroke-risk, is also a common cause of admissions, and there are 50,000 new cases each year in the UK.  Atrial flutter commonly causes recurrent admissions, but can be easily cured by catheter ablation, and this quickly leads to financial savings.


Diagnosis.

NICE guidelines require an ECG diagnosis of AF, but this is currently somewhat time-consuming and laborious in primary care.  Better technology is needed, and configured in an Integrated Technology Network that supports use at all levels.  Thirty QoF points are available for pulse-check, ECG-confirmation and onward referral of patients with AF.


Simple things first.

Established AF is either persistent, (if it has lasted more than 7 days, and cardioversion is being considered), or chronic, if cardioversion has been ruled out, and a patient is to be managed in long-term AF with assessment, rate-control, and anti-thrombotic measures.  Warfarin should be given in persistent/chronic AF:-


-to all eligible patients over 65

-to patients under 65 with cardiovascular disease/risks, e.g. diabetes, CHD


Treatment with warfarin has a drug cost of 70p/month, and results in a 60% reduction in fatal and non-fatal stroke.  Practice-based INR-testing solutions is now available.


Chronic AF

Chronic AF is associated with stroke, heart failure and, increasingly, cognitive dysfunction, probably related to multiple small thromboemboli.  Warfarin should keep the INR between 2 and 3.  Heart rates at rest and with exercise should be appropriately controlled.  Digoxin does not control the exercising heart rate in AF.  Β-blockers and calcium antagonists that affect the AV-node are usually needed.  Occasionally, patients with poor rate-control need a pacemaker and ablation of the AV-node to avoid heart failure.  This is very good for symptoms, reduces drug-consumption, reduces hospital admissions and improves quality-of-life significantly.



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Cardioversion.

Direct-current cardioversion should be done in all cases with the highest intention of gaining the best outcome, although this is rarely the case.  Cardioversion can be done quite safely by trained specialist nurses using conscious sedation as a day case.  Patients should be prepared with a drug such as amiodarone for at least 2 months, and warfarinised.  Shocking patches should be placed AP, and biphasic shocks should be given with a starting energy of at least 200 Joules.  Amiodarone and warfarin should then be continued for at least 2 months.


Paroxysmal AF.

Paroxysmal AF PAF is often much more troublesome than chronic AF, and is also a common cause of admission to hospital.  The aim of treatment is suppression of AF episodes.  The stroke risk in PAF is uncertain, and certainly low in patients with structurally normal hearts.  Aspirin is advisable in all cases, and warfarin on a case-by-case basis over 65.


Suppressing AF.

In patients with PAF and a normal heart, flecainide is the drug of choice, but it is not innocuous.  BMF recommendations are for commencement in hospital.  Patients should be commenced by a cardiologist, ideally with an interest in heart rhythm care, (cardiac electrophysiologist).  There is a risk of flecainide encouraging atrial flutter with very fast heart rates.  This can lead to death.  Patients should combine flecainide with a b-blockers or calcium antagonist, at lest initially.  In patients with known or suspected heart disease, amiodarone is the best drug for suppressing PAF.


Amiodarone – why not for everybody?

Amiodarone has very important side-effects.  It is hardly excreted at all, and is retained in all tissues.  It can damage the skin, thyroid, eyes, brain, nervous tissue, liver and lungs.  It may cause allergic responses in those sensitive to iodine.  It has an increased risk of cauising damage over time, because of aggregate accumulation.  When stopped, it has a half-life of 5 weeks, and it is therefore difficult to withdraw quickly if there is a bad reaction or toxicity.


Dronedarone – not a miracle drug.

Recently, a new drug has become available, called dronedarone.  This is like amiodarone in it’s mode of action, but it does not contain iodine, and therefore does not have the many toxic side-effects of amiodarone.  Dronedarone is moderately effective in preventing recurrences of atrial fibrillation.  It shouldn’t be used in chronic atrial fibrillation.  It should not be used in patients with heart failure.  It will find it’s place in suppressing bouts of atrial fibrillation in some patients, but it is not a miracle drug and it may not be a first line drug for many doctors treating atrial fibrillation.


Catheter ablation.

Many patients with PAF, and a few with chronic AF are now eligible for a catheter ablation approach to stopping PAF.  This takes about 3 hours, can be done under sedation, and targets the irritable trigger areas in the left atrium where the 4 pulmonary veins drain into that chamber.  Overall success rates are 80-90%.  There is a risk of stroke during the procedure, but the natural history is for deterioration of PAF into chronic AF, so that there is a risk of stroke if nothing is done to prevent AF.  Catheter ablation is only done by some cardiologists with heart rhythm training – trained cardiac electrophysiologists.

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