Atrial Fibrillation symptoms

A significant proportion of people, perhaps as many as a third, have no obvious symptoms from atrial fibrillation. This may be because they are truely asymptomatic - their body compensates, they can exercise normally and they are blissfully unaware of the change in their heart rhythm. For others it may be that they have noticed a change, but they can't put their finger on it. They put it down to getting older and they carry on without a second thought.

At the other end of the spectrum there are some people whose atrial fibrillation is extremely debilitating. As soon as it occurs they feel dreadful and may even call an ambulance or take themselves to the Emergency Department. For these unfortunate individuals it is quite clear what the problem is.

Most people are somewhere in the middle. Their atrial fibrillation causes some symptoms, they don't feel well are have to limit their activity, but they can get on with day to day life even if it is at a slower pace than usual.

The symptoms from atrial fibrillation will only occur during the arrhythmia. They will be there all the time in people with persistent atrial fibrillation but should come and go in people with paroxysmal atrial fibrillation. It is important to realise that no matter how bad you feel during an attack, atrial fibrillation almost never damages the heart muscle or causes injury to it (the only exception being tachycardia cardiomyopathy which occurs if there is a very rapid heart rate for days on end)

Atrial fibrillation can cause symptoms through two mechanisms. The loss of atrial contraction means that the atriums are not helping to push blood into the ventricles. This can reduce the amount of blood that the left ventricle pumps out around the body by up to one third. This reduction in cardiac output may manifest as general fatigue, tiredness, reduced exercise capacity and just generally feeling less energetic and lively. Atrial fibrillation may also make the ventricles pump in a fast and chaotic manner. This rapid, irregular pulse can cause palpitations, breathlessness, chest tightness and sometime light-headedness or dizziness, particularly with exertion.

It is important to recognise the two different mechanisms that cause symptoms - the loss of atrial contractility and the rapid, irregular ventricular rate, as the role of each of these mechanisms will determine the type of treament that is most likely to succeed in abolishing symptoms

Rate control

One strategy to abolish symptoms is to aim to control the speed at which the ventricles pump during episodes of atrial fibrillation and thus try and mask or hide the fact that the arrhythmia is present. If the filtering through the AV node can be controlled so that the ventricles pump at 60-90 beats per minute when resting and only accelerate slowly during exercise and never go too fast, it should be possible to prevent any symptoms that result prom a rapid ventricular rate (such as palpitations, chest ache or dizziness). Keeping the heart rate at rest below 100 bpm will also protect the heart from developing tachycardia cardiomyopathy. It is important to note that rate control strategies do not try to prevent the atriums from fibrillating - they just try to make you unaware that it is happening. Any symptoms that result from the loss of atrial contraction during fibrillation will remain. The stroke risk will also remain unchanged.

A rate control strategy has the advantage of generally being slightly easier to achieve and uses simple methods. Typically, rate-controlling drugs such as betablockers, calcium channel blockers and digoxin may be used individually or in combination. Often the drugs are well tolerated but occasionally they may cause side effects. If they are ineffective or cause severe sife effects an alternative form of rate control is AV node ablation and pacemaker implant. With this simple procedure the AVN is destroyed to create complete heart block and prevent any electrical impulses from reaching the ventricles. It means that a pacemaker has to be implanted to tell the ventricles how fast to beat. It can guarantee they never go too fast or too slow. This is an irreversible procedure that means the person will require a pacemaker for the rest of their life.
Click on the different treatments mentioned above to find out more about them.

Rhythm control

The alternative stragegy is to try to keep the heart in normal sinus rhythm and prevent atrial fibrillation from happening in the first place. For people in persistent atrial fibrillation this will mean first getting the rhythm back to normal using a process called cardioversion. A cardioversion is usually performed by delivering an electric shock to the heart through paddles stuck to the outside of the chest during a brief, light general anaesthetic. It "resets" the heart rhythm back to normal, but on it's own it doesn't do anything to the atriums to stop fibrillation from returning.

Antiarrhythmic drugs are used to try and prevent atrial fibrillation from returning after a cardioversion or to reduce or abolish paroxysmal atrial fibrillation episodes. Occasionally an antiarrhythmic drug may even pharmacologically cardiovert someone in peristent atrial fibrillation back to normal rhythm without the need for the electrical cardioversion.

If successful, a rhythm control strategy should be the most effective form of symptom treatment as it will abolish symptoms resulting from the rapid irregular ventricluar rate and the loss of atrial contractions. Unfortunately this can prove to be quite challenging. In people with persistent atrial fibrillation, 2/3 will be back in atrial fibrillation 6 months after a cardioversion if they don't take any drugs. Even if they do take the strongest drug available, Amiodarone, 1/2 will be back in atrial fibrillation after 6 months. Drugs such as Flecainide, Sotalol and Dronedarone can be taken to try and prevent paroxysmals of atrial fibrillation. In a few fortunate individuals they work perfectly. In a many these drugs are able to reduce the frequency and duration of attacks, which may be enough to keep people happy, but in a significant proportion of people antiarrhytmic drugs have no appreciable effect. They also tend to be more potent and have to ability to cause a wide range of side effects.

When antiarrhythmic drugs don't work or cause limiting side effects, if a rhythm control strategy needs to be pursued an alternative treatment is catheter ablation (pulmonary vein isolation or left atrial ablation). This procedure seeks to alter the atriums by destrying key areas of atrial muscle that are believed to be responsible for initiating and maintaining attacks of atrial fibrillation. When compared to antiarrhythmic drug treatment, catheter ablation has been shown to be far superior at treating symptoms in patients who are highly symptomatic. Catheter ablation is an interventional procedure however and any operation has risks invlolved that need to be justified. It is not successful in 100% of people and many require 2 or more ablation procedures to get the desired result.
Click on the different treatments above to find out more about them.

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