Atrial fibrillation

Atrial fibrillation is an abnormal heart rhythm originating in the upper chambers of the heart (the atria). It’s the most common type of heart rhythm problem (or arrhythmia), and is thought to affect more than 100,000 people in Ireland. Although it can be benign, and usually isn’t life-threatening, atrial fibrillation increases the risk of a stroke, and often requires treatment.

What is atrial fibrillation?

The word fibrillation means ‘quivering’, and this is essentially what’s happening in a heart with atrial fibrillation (or AF). Heart rhythm is controlled by electrical impulses originating from the heart’s natural pacemaker – the ‘sinus node’. These impulses cause the muscular walls of the heart to contract at regular intervals, pumping blood around the body. In AF, the electrical signals are random or chaotic. This causes the upper chambers of the heart to contract abnormally (or fibrillate). The result is an irregular heartbeat – often too fast, or sometimes too slow – which reduces the heart’s pumping efficiency.

What causes atrial fibrillation?

The underlying cause of AF is often very difficult to uncover. But it can potentially be associated with a range of other heart conditions, including:

  • High blood pressure (hypertension)
  • Heart failure (the heart isn’t pumping strongly enough)
  • Heart valve disease
  • Atherosclerosis (clogging of the arteries)
  • Cardiomyopathy (a disease of the heart muscle)

AF is also sometimes associated with certain other medical conditions, such as lung diseases (for example, pneumonia or chronic bronchitis), asthma, a thyroid gland abnormality and diabetes. It may possibly be triggered by other circumstantial factors as well, including excessive alcohol consumption, drinking caffeine, smoking, or obesity.

What does atrial fibrillation feel like?

AF doesn’t always cause symptoms – it’s possible to have the condition without being aware that it’s present. In these cases, it’s often picked up inadvertently in the course of another medical check-up. For other patients, however, AF can cause a number of uncomfortable symptoms, ranging from a palpitation (a feeling of the heart beating in the chest) to chest pains. Since AF can cause the heart’s output to drop by up to 20 percent, it can also leave you feeling tired, dizzy or short of breath. With or without symptoms, AF can manifest itself in several different ways:

Paroxysmal atrial fibrillation (PAF) – where the irregular rhythm occurs temporarily – perhaps from hours to a day or two – before disappearing, usually without any treatment

Persistent AF – where the irregular rhythm remains for a longer period of time, perhaps a week or more, before disappearing (if the problem persists for much longer – perhaps a year or more – we call it ‘longstanding persistent AF’)

Permanent or Long–standing Persistent AF – where the irregular rhythm is present all the time

A separate condition called atrial flutter can cause similar symptoms to atrial fibrillation (and indeed is present in around 30% of people with AF). It’s a less common heart rhythm problem than AF, with a similar range of treatments. For more information about atrial flutter, click here.

Who gets atrial fibrillation?

AF is most common in older people. Somewhere between four and seven percent of people over the age of 65 suffer from the condition. It’s also more usually seen in men than in women. As mentioned above, people who have certain other medical and heart-related conditions have a higher risk of developing AF.

What happens next?

One of the main concerns with atrial fibrillation is a raised risk of a stroke. When blood isn’t flowing normally around the heart, it can potentially start to pool and form clots. These clots can then pass into smaller blood vessels around the body, such as in the brain, where they may restrict or block the flow of blood (ischaemia). While it’s rare for people with lone AF (where no other heart problem is present) to suffer serious medical complications, patients with other underlying conditions may be at a significantly heightened risk of suffering a future stroke. For this reason, it’s sometimes necessary to treat AF with anticoagulants to reduce clotting; this could include medicines like edoxaban, apixaban, dabigatran or rivaroxaban, that have largely replaced warfarin in this condition.

Depending on your situation, we may also want to consider an approach that involves altering the rate or rhythm of your heart:

Heart rate control – this approach focuses on slowing down the heart’s pulse rate. There are a number of medicines we can use for this; they include betablockers, calcium channel blockers and a ‘cardiac glycoside’ medicine called digoxin.

For some patients this may be required in the long term where medication has not worked to slow the heart sufficiently or the side effects of medication are not tolerated. This also requires a pacemaker to be present or inserted initially. This is called AV node ablation and pacemaker insertion for atrial fibrillation rate control.

Heart rhythm control – this approach focuses on returning the heart to its natural rhythm: the so-called ‘sinus rhythm’. There are several ways to do this. One involves a course of medication, such as amiodarone, flecainide or betablockers. Another involves a procedure called an electrical cardioversion, where we use a controlled electrical current to ‘re-set’ the heart and restore it to its normal rhythm. A further approach involves a procedure called an ablation; this is where a specialist cardiologist creates an area of scar tissue inside the heart, which stops it from producing or conducting the irregular impulses that cause or sustain AF.