Episodes of atrial fibrillation can be very troublesome, but are rarely dangerous. The most common symptoms are palpitations, a fast and irregular pulse, shortness of breath and reduced exercise capacity. The intensity varies. Some are severely affected, while others notice nothing.
What happens in the heart?
During atrial fibrillation there is fast and chaotic electrical activity in the atria. It has been compared to an electrical storm. The AV node is “bombarded” with electrical signals, but fortunately does not let all of them through to the ventricles. How well the AV node conducts determines how fast the heart beats during atrial fibrillation.
Who gets atrial fibrillation?
Some conditions increase the risk of atrial fibrillation, for example an overactive thyroid, infection, heart valve disease, heart failure, high blood pressure and obesity. The incidence increases with age. Among 70-year-olds about 1 in 10 have atrial fibrillation, while it is rare in 20-year-olds. Much suggests that hard endurance training in middle age makes you more susceptible.
When atrial fibrillation is diagnosed, a limited work-up is often done to look for underlying causes. If a cause is found and corrected, some people get rid of the arrhythmia. Most often, however, no definite cause is found.
Blood clots and blood thinners
When the heart changes from normal rhythm to atrial fibrillation, the atria lose their pumping force. This changes the blood flow through the atria so that blood clots can form. After an individual assessment by the treating doctor, some will be recommended blood-thinning treatment.
Treatment with medication
Many need treatment because they have significant symptoms and there are no other diseases that can be corrected. Most are first recommended medication. The aim is either to slow the heart rate or to prevent episodes. The first is called rate control, the second rhythm control. Treatment often contains elements of both.
Rate control. Medicines that slow the heart rate usually relieve symptoms during episodes. Examples are metoprolol (a beta blocker), digitalis and verapamil (a calcium antagonist). Beta blockers and calcium antagonists are also widely used for high blood pressure and can therefore be useful for several reasons. The drawback is that they can cause side effects, and none of them can be used by people who already have severe conduction disorders or a very slow heart rate.
Rhythm control. Here more “potent” drugs are used to reduce the number of episodes, for example flecainide, amiodarone and dronedarone. Many are helped, but these can also cause side effects. We know of conditions that increase the risk of the most serious side effects, but the assessment can be complex, and treatment should probably be started by a specialist in cardiology or internal medicine.
Atrial fibrillation ablation
Many have significant symptoms even with the most effective medicines, and others get intolerable side effects. Ablation may then be an option. In paroxysmal atrial fibrillation, ablation is today also recommended as first-line treatment in selected patients, without first trying medication.
Why does it work?
In people with paroxysmal (intermittent) atrial fibrillation, episodes are often triggered by rapid electrical impulses “fired” in the left atrium. The impulses often come from small islands of heart muscle cells inside the blood vessels that carry oxygen-rich blood from the lungs to the left atrium (the pulmonary veins). If episodes last for weeks or months, more and more of the atrial wall is altered, and gradually larger parts of the atria can start or maintain the fibrillation. In many people the episodes become longer and more frequent, until fibrillation is present all the time.
Ablation works best in paroxysmal atrial fibrillation. It is also performed in persistent atrial fibrillation, but the results are poorer. In permanent atrial fibrillation, ablation aimed at restoring normal rhythm is usually not recommended. For these patients AV node ablation may be an alternative.
Today’s technique was mainly developed by two competing groups, in Milan and Bordeaux. The aim is to create rings around the pulmonary veins that block electrical activity. This used to be done by burning (radiofrequency) or freezing (cryo). Today pulsed field ablation (PFA) is increasingly used, in which short, powerful electrical pulses destroy the heart muscle cells while sparing the surrounding tissue.
In persistent fibrillation, other areas where the arrhythmia is thought to start or be maintained are sometimes also ablated. Whether and how this should be done is debated and the subject of much research.
Where is ablation done?
In Norway this treatment is provided in specially equipped laboratories at the University Hospital of North Norway, St. Olav’s Hospital, Haukeland University Hospital, Akershus University Hospital, IbsenSykehusene and Rikshospitalet. Some are also treated at private clinics or in Denmark, funded by insurance or out of pocket.
Most are referred from a hospital outpatient clinic or a private specialist in internal medicine or cardiology.
How it is done
We want patients to take blood thinners before the procedure. Detailed instructions are given in the preliminary consultation with a doctor at the hospital.
On admission, the patient is received by a doctor and nurse, who explain what will happen, the purpose of the procedure and possible complications. An ultrasound of the heart is often done, both with an ultrasound probe in the oesophagus and in the usual way from the outside. You must fast for a few hours before the ultrasound and the procedure. In some patients the examination from the oesophagus is replaced by a CT scan of the heart.
Before the procedure, painkillers and sedative tablets are usually given. During the procedure the patient lies on an operating table surrounded by X-ray equipment and computer screens, with ECG electrodes, a blood pressure cuff, a clip on the finger measuring oxygen saturation and an intravenous cannula in the hand. Most are awake but drowsy, and we give more painkillers and sedatives as needed. From autumn 2026 the procedure is increasingly performed under general anaesthesia at Rikshospitalet.
The procedure itself can be divided into three phases:
- Access to the heart. We give local anaesthesia around the large vein in the groin, usually only on the right side. Using a needle, guide wires are introduced into the vein, and short, flexible plastic tubes are threaded over them. Through these, catheters (electrodes) are passed up to the heart under X-ray guidance. The electrodes pick up electrical signals from inside the heart and can also deliver short electrical pulses that make the heart beat.
- From the right to the left atrium. A longer sheath is advanced to the right atrium. Through it a needle is passed and used to puncture the wall between the atria. The ablation catheter is then advanced into the left atrium. A three-dimensional model of the atrium is often created in the computer and used to guide the treatment.
- Ablation. Rings are created around the openings of the pulmonary veins. It is then checked that the rings are complete, so that the pulmonary veins are electrically isolated from the rest of the atrium. Finally all equipment is withdrawn, and pressure is applied to the groin for a while to stop the bleeding.
During the procedure a blood thinner (heparin) is given directly into the bloodstream, and the degree of anticoagulation is measured regularly. This is because ablation leaves wound surfaces where clots can form, which at worst can come loose and cause a stroke.
Results
Many studies have looked at how patients do after atrial fibrillation ablation. Results vary somewhat, but most report that about 70 per cent are no longer troubled by atrial fibrillation one year after the procedure. Most studies have been done in patients with paroxysmal atrial fibrillation. In persistent atrial fibrillation the results are poorer.
Complications
As with any procedure, things can go wrong. Between 1 and 2 per cent of those who undergo atrial fibrillation ablation have serious complications. Less serious events are more common. Adverse events can occur however well the procedure is prepared. An important part of the assessment before ablation is therefore whether the risk is reasonable in relation to the chance of fewer symptoms.
- Bleeding from the puncture site is the most common. There is often blue and later yellow discolouration in the groin, which goes away by itself. Rarely, serious bleeding occurs in the groin or into the pericardium (the sac around the heart). Bleeding into the pericardium happens during or just after the procedure and can make the patient very unwell, but it can be treated: a plastic tube is inserted into the pericardium under ultrasound guidance and the blood is drained. The patient usually recovers immediately. Very rarely the chest must be opened to repair the hole.
- Stroke. Blood clots can at worst cause a stroke. Blood thinners reduce the risk, and stroke with lasting disability is rare, but it does occur.
- Narrowing of the pulmonary veins can occur, but rarely causes symptoms or requires intervention.
- Injury to the oesophagus. The oesophagus lies only a few millimetres behind the left atrium. A feared complication is that a hole is burned from the heart into the oesophagus. All operators are aware of this, and fortunately it happens very rarely.
- Injury to the nerve to the diaphragm occurs, but usually heals by itself and rarely causes serious symptoms.
All treatment involves risk. Fortunately the vast majority do well.
Atrial fibrillation and heart rate monitors
Many watches can now alert you to possible atrial fibrillation. During atrial fibrillation, measurements of heart rate variability (HRV) become meaningless, because the variation is no longer controlled by the nervous system. Read more under Pitfalls in HRV measurement.