How is rhythm control used to treat atrial fibrillation?

The heart beats regularly and more slowly again after cardioversion. Symptoms like palpitations, dizziness, and weakness get better and the heart is under less strain.

But cardioversion also has disadvantages: It temporarily increases the risk of a stroke. To minimize that risk, you will be given medication to stop the blood from clotting (anticoagulants) before and after cardioversion.

The atrial fibrillation often doesn’t go away for good, either. The risk of it returning is especially high

• in older age (over 70 years),
• in women,
• if cardioversion has already been done in the past,
• if the atrial fibrillation was already there a long time before cardioversion,
• if you have COPD,
• kidney disease, or
• a damaged or weakened heart muscle.

The electrical energy needed for cardioversion is delivered via electrodes that the doctor sticks or presses onto your chest. This stimulates all of the heart muscle cells at once, and they then relax again at the same time. The uncontrolled signals circulating in the atrium then subside. The atrial fibrillation stops, and the heart starts to beat in its normal rhythm again.

Electrical cardioversion is generally suitable if you have decided to have rhythm control: It restores the heart’s normal rhythm in almost 90 out of 100 people. That is why it is considered to be more effective than cardioversion with medication.

Electrical cardioversion is usually used right away in cases where the heart rhythm disorder causes severe circulatory problems (cardiovascular shock). A special examination called echocardiography is done beforehand to make sure that there are no blood clots in the heart.

The situation is less urgent if the circulation of blood is stable. This examination is mainly used to be able to start treatment with anticoagulants before cardioversion to prevent stroke. If the atrial fibrillation has started recently, it may be worth waiting two days because the heart often returns to its normal rhythm by itself in that time. Cardioversion is often only performed three weeks after starting treatment with anticoagulants in people who have an increased risk of stroke and longer-term atrial fibrillation.

The electrical signal itself hardly has any side effects. In rare cases, the electrodes may cause minor burns. The signal is triggered while the heart is being monitored using ECG and only sent when the heart is “ready.” That means it usually doesn’t cause any other heart rhythm problems. In rare cases the heart rate might be slowed down following electrical cardioversion.

The disadvantage of electrical cardioversion: You will be given a short, mild anesthetic so that the impulse doesn’t hurt. That can cause side effects like nausea or circulation problems. People who do not tolerate the anesthetic can choose to have cardioversion with medication.

If electrical cardioversion isn’t possible, the heart’s normal sinus rhythm can also be restored by taking certain antiarryhthmic medications once or twice. They have different advantages and disadvantages depending on the active ingredient:

• The drugs flecainide and propafenone can be taken as tablets or injected intravenously. They restore the heart’s normal rhythm in about 60 to 80 out of 100 people. But it usually takes a few hours to take effect. The medications are a bit more effective if injected. They are not suitable for people who also have coronary artery disease. They can also cause blood pressure to drop too low and trigger other types of heart rhythm disorders, especially atrial flutter.
• In rare cases, vernakalant or amiodarone are used for cardioversion. Vernakalant is always injected and has a faster effect than flecainide and propafenone: It is not suitable for people with a weak heart. Nor is it suitable for people who have recently had a heart attack, or who have low blood pressure or heart valve disease. Side effects include reduced blood pressure and other types of heart rhythm disorders such as ventricular tachycardia. Amiadorone is less effective than the other medications and it can take a number of days for the heart to return to its normal rhythm. Side effects include trembling, impaired vision, skin, liver, lung, thyroid and circulation problems, and heart rhythm disorders.

Doctors try to stabilize the sinus rhythm following cardioversion, usually with medication or catheter ablation. In rare cases surgery might be an option. But atrial fibrillation can’t always be stopped from coming back: Depending on which procedure is carried out, atrial fibrillation returns in around 50 to 70 out of 100 people within three years despite stabilizing treatment.

That is why detailed examinations have to be done before stabilization treatment to see what the chances of success are. For instance, an enlarged left atrium or kidney damage both increase the risk of atrial fibrillation returning despite catheter ablation.

The antiarrhythmic agents amiodarone, propafenone, and flecainide that are also used for cardioversion with medication can be taken as tablets in the long term to keep the heart’s normal rhythm. Another option is the active ingredient dronedarone. It is considered to be less effective, but is tolerated better than amiodarone. But dronedarone is not suitable for people with heart failure.

During catheter ablation, a small amount of tissue on the inner wall of the heart where the blood vessels from the lung enter the left atrium is destroyed (ablated) using electrical energy or extreme cold. This process turned the ablated areas into scar tissue, stopping the abnormal signals from spreading through the heart.

This procedure typically involves a hospital stay of one or two days. First of all, a local anesthetic is applied to the skin in the groin before a catheter is inserted into a large blood vessel. You will be given a short, mild sedative for the ablation itself. The doctors can move all of the instruments they need up to the heart through the catheter tube. To treat atrial fibrillation, the tip of the catheter is pushed through the cardiac septum into the left atrium where the heart rhythm problems are most likely to start.

The most common side effect of catheter ablation is bruising in the groin area, where the catheter was inserted. But the procedure can also cause other complications such as injuries to the heart or blood vessels, pericardial effusion or stroke. That is very rare, but they can be life-threatening and may require emergency treatment.

A large study involving over 2,000 participants looked into the advantages and disadvantages of catheter ablation and treatment with medication. The study lasted several years.

The main results that other studies also confirmed were:

• Both treatment approaches relieved the symptoms in most people.
• There was a noticeable improvement in 90 out of 100 people who had a catheter ablation procedure, and in 80 out of 100 people who were treated with medication.
• None of the treatments can guarantee that the heart rhythm will stay normal: About 50 out of 100 participants developed atrial fibrillation or another atrial heart rhythm disorder, such as atrial flutter, within three years of an ablation. This happened in about 70 out of 100 people who took antiarrhythmic agents. About 20 out of 100 people had more than one catheter ablation over time.
• The medication caused side effects in 4 out of 100 people. 1 out of 100 people had a severe complication such as a life-threatening heart rhythm disorder, or damage to the liver or lungs.
• About 70 out of 1,000 people who had an ablation procedure had side effects such as bruising where the catheter was inserted, or temporary chest pain. About 20 out of 1,000 ablations led to life-threatening complications; fewer than 2 out of 1,000 people died during or shortly after the procedure.
• People who are first treated with ablation can still need antiarrhythmic agents later, perhaps because the heart rate can’t be kept normal in the long term even after the procedure. But study participants who had had ablation needed less antiarrhythmic agents than those participants who were treated with medication from the beginning.
• Life expectancy and the risk of complications such as stroke were the same in all participants regardless of the type of treatment.

Other studies showed that catheter ablation increased life expectancy and led to fewer complications than treatment with medication in people who also have heart failure.

Heart surgery to permanently return the heart's rhythm to normal is mainly an option if

• no other treatment options are possible or were unsuccessful, and
• heart surgery is already planned anyway, perhaps because a heart valve has to be operated on.

As with catheter ablation, a small amount of tissue is destroyed or cut into and then sewn back up to form small scars. The procedure can be carried out as open heart surgery or as non-invasive (keyhole) surgery. Side effects can include bleeding, damage to organs and nerves, heart rhythm disorders, or problems with anesthetic.