What Is Atrial Fibrillation?

Atrial fibrillation, also called AFib or AF, is the most common type of heart arrythmia. In atrial fibrillation the heart rate typically becomes fast and irregular. Atrial fibrillation is usually not immediately life-threatening but if it remains untreated, it may for instance increase the risk of stroke and cause heart failure.

Common symptoms of atrial fibrillation include irregular heartbeat, anxiety, dizziness, fatigue and reduced performance. There are individual differences and variation in the occurrence of symptoms. Atrial fibrillation may also often be asymptomatic (i.e., without any symptoms).

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Types of atrial fibrillation

Atrial fibrillation can occur in different types. It can be divided into four main types based on recurrence and duration:

  1. Paroxysmal atrial fibrillation: an episode with short duration, lasting a couple of minutes or hours, after which the heart rate returns to normal on its own.
  2. Persistent atrial fibrillation: an episode lasting over a week and does not stop on its own. In that case an attempt needs to be made to restore normal heart rhythm either with electrical or pharmacological cardioversion.
  3. Long-term persistent atrial fibrillation: an episode typically lasting over a year, when also the use invasive treatments may be considered to restore normal heart rhythm.
  4. Permanent (chronic) atrial fibrillation: in this condition normal heart rhythm cannot be restored in spite of treatments. In this case, atrial fibrillation is accepted as a permanent condition and attempts to convert AFib to normal sinus rhythm are no longer pursued.

In addition to these classifications, also the terms “lone atrial fibrillation” or “transient atrial fibrillation” are being used. They refer to the occurrence of atrial fibrillation in individuals who do not have any heart disease but who experience an episode of AFib triggered by some transient factor.

Normal heart rhythm

The normal rhythm of the heart is called sinus rhythm, with a usual heart rate at rest of 60 to 80 beats per minute. The rhythm originates, when an electrical impulse is generated in the sinus node located in the wall of the right atrium. The sinus node acts as the natural pacemaker of a healthy heart and generates an electrical impulse stimulating the heart to contract, i.e., to pump blood. As a result of the depolarization of the heart muscle cells (myocardial cells) the generated electrical impulse travels from the sinus node through the atria. This makes the atria to contract and pump blood in the ventricles. The impulse moves on through the atrioventricular node (AV node) in the septum, which is the wall diving the left and right ventricles of the heart. The impulse then travels through two branches: one branch goes to the right ventricle, another to the left ventricle. These two main branches divide further into a system covering the whole heart muscle. As a result of the electrical impulse, the heart muscle contracts and pumps blood from the heart into the circulation system. After the contraction period (systole) the contraction comes to an end and the heart muscle returns to a period of relaxation. This is called diastole. The sinus node accelerates the heart rate when needed, for instance in connection with physical exertion.

Onset and mechanism of atrial fibrillation

Atrial fibrillation is the most common type of heart arrhythmia and no less than 25% of the global population is affected by it during their lifetime. In atrial fibrillation the normal rhythm of the heart is replaced by a more rapid electrical activity, which tries to make the heart contract up to 450-600 times per minute. The heart muscle located in the atria is not able to contract in such a rapid manner. The atria remain fibrillating (from which the term atrial fibrillation is derived).

As the electrical impulse in atrial fibrillation reaches the AV node located between the atria and the ventricles, it slows down the rhythm on its’ way to the ventricles. Thus, in newly onset atrial fibrillation the heart rhythm conducted to the ventricles is clearly increased and usually irregular. The rapid heart rhythm in atrial fibrillation stimulates the AV node. Thus, the electrical impulses sent by the atrium will randomly travel into the ventricle, and this results in an irregular heart rate. The heart rate may be for instance 130-160 beats per minute. Especially in paroxysmal atrial fibrillation the heart rate is rapid, as described above. However, over time (for instance during a few months) the heart rate in atrial fibrillation often slows down, being 80-120 beats per minute. There may be considerable individual variation in the heart rate levels during atrial fibrillation.

Predisposing factors for atrial fibrillation

Age is the most significant predisposing factor for atrial fibrillation. For those over 50 years of age, the risk of atrial fibrillation will more than double per each 10 years of age. In addition to age, the predisposing factors can be divided into cardiac factors and non-cardiac factors. The most significant cardiac factors are high blood pressure, heart failure, valvular heart disease and coronary artery disease (CAD). Of the non-cardiac factors especially diabetes, obesity, sleep apnea, disorder of thyroid function, chronic pulmonary diseases and unhealthy lifestyle predispose the patient to atrial fibrillation.

In individuals who do not have any heart disease, transient atrial fibrillation can be triggered for instance by the following factors: viral pericarditis or myocarditis, drug abuse, drinking too much coffee or energy drinks or drinking too much alcohol. In these cases, the heart rhythm often returns to normal, when the triggering factor is removed or taken care of.

Even though atrial fibrillation is an arrhythmic condition which in itself requires treatment and attention, it can also be a symptom of another heart disease, such as heart failure, valvular heart disease or coronary artery disease. When atrial fibrillation occurs, it is vital to seek medical assistance. Only this makes it possible to find the underlying causes and enables proper treatment.

Detection of atrial fibrillation

To enable diagnosis of atrial fibrillation, it needs to be detected on an electrocardiogram (ECG). For this reason, it is very difficult to diagnose paroxysmal atrial fibrillation, as the heart rhythm often returns to normal before any detailed examinations have been made. Considering this, smart technological devices to be used at home for AFib detection (blood pressure meters, mobile applications and smartwatches recording heartbeat and rhythm) may be a great help in detecting atrial fibrillation.

Read more about how to detect atrial fibrillation by yourself

Is atrial fibrillation dangerous?

Atrial fibrillation is dangerous. It is not immediately life-threatening like ventricular fibrillation or myocardial infarction, but being persistent for a long time makes it dangerous. Long-term persistent atrial fibrillation is a predisposing factor for stroke and heart failure. The fact that atrial fibrillation can be completely asymptomatic makes it even more dangerous. Research shows that up to 40% of diagnosed AFib cases are asymptomatic. It is essential that atrial fibrillation is not left untreated and that the patient seeks medical attention. This enables the establishment of an individual treatment strategy.

During atrial fibrillation the atria do not contract properly and due to this, blood may pool there. When blood has opportunity to pool, it also has the opportunity to clot. At some point blood clots may be pumped out of the heart and travel through the bloodstream. This does not happen immediately: only in case atrial fibrillation has persisted for longer than 48 hours. When a blood clot travels to the brain, it blocks blood vessels, thus disturbing normal circulation in the brain. In this area of the brain where normal blood supply is blocked, brain cells start to be damaged by the lack of oxygen and nutrients.

Untreated long-term persistent atrial fibrillation can impair heart function and predispose the patient to heart failure. Research shows that atrial fibrillation can increase the risk of heart failure up to nearly 400%. Congestive heart failure is not a disease as such but a syndrome, in which the heart is not able to pump enough blood to meet the demands of the body. As the heart is not able to pump blood efficiently enough, the oxygen supply of the body deteriorates. Due to this, the symptoms first appear during exercise, but as heart failure progresses, they may occur also during light activities or even at rest. Studies show that almost half of all patients who suffer from heart failure die within five years from the onset of symptoms. There is individual variation caused by several underlying factors. Atrial fibrillation is only one factor which predisposes the patient to heart failure. Other predisposing factors include for instance cardiovascular disease, previous myocardial infarction and high blood pressure.

Symptoms of atrial fibrillation

There is considerable variation in the symptoms of atrial fibrillation, ranging from a completely asymptomatic condition to severe symptoms. Many studies have been conducted on the prevalence of symptoms. According to several studies more than half of all people with atrial fibrillation do not recognize any symptoms or are asymptomatic. In fact, a study conducted in Turku University Central Hospital shows that over one third of those patients who were hospitalized urgently because of a stroke, had completely asymptomatic atrial fibrillation. Thus, stroke was the first manifestation of atrial fibrillation in these patients.

The most typical sensations associated with atrial fibrillation include irregular heartbeat, palpitation, anxiety, dizziness, fatigue and reduced performance. In long-term persistent atrial fibrillation, the sensations are often mild and some people do not notice them at all. Paroxysmal atrial fibrillation can be very disturbing and cause anxiety. It is understandable that the first episode of atrial fibrillation may feel rather frightening.

Prevalence of atrial fibrillation

It is estimated that there are 230,000 patients diagnosed with atrial fibrillation in Finland. In reality the number of those with atrial fibrillation is considerably higher, as the disease is often asymptomatic. Every year approximately 11,500 people in Finland have their first stroke. Over 80,000 Finns (1.5% of total population) have suffered a stroke. Approximately one third of these strokes are related to atrial fibrillation. If atrial fibrillation was detected in time, more people would be able to avoid stroke.

Of all people aged 40 years or above, one in four will have an episode of atrial fibrillation in their lifetime. The prevalence of atrial fibrillation increases rapidly with age. Studies show that approximately 0.4% of people aged under 60 years suffers from atrial fibrillation but in people aged 75 years or above, the prevalence is over 10%.

How can I detect atrial fibrillation myself?

There are two alternatives for detecting AFib at home: checking your pulse or using a monitoring device meant for consumers.

Checking your own pulse by hand is a cheap and easy way of finding out, if your heart has a normal sinus rhythm. A good way of noticing irregular heart rate is to say out loud “now” every time your heart beats. The drawback of this method is that if you notice an abnormal heart rhythm, it is impossible to say, which type of arrhythmia it is (extrasystolic beats, atrial fibrillation, atrial flutter, tachycardia or bradycardia). However, it should be noted that atrial fibrillation is the most common of significant arrhythmias.

When using an AFib home monitoring device the most important thing is to ensure that the device in question is a CE certified medical device meant for detecting atrial fibrillation. This way you can be sure that the device in question has been found functional in demanding clinical trials and has been checked and approved by the authorities.

There is a wide variety of CE certified devices and their number is continuously increasing. These devices can be generally classified into following categories: mobile applications utilizing built-in sensors included in smartphones, technologically-advanced blood pressure meters and wearable smart devices (watches, wristbands, jewelry).

Examples of CE certified devices for atrial fibrillation detection:

  • Solutions which measure heart movements: Mobile app CardioSignal (€4.17/month –€7.99/month depending on the chosen subscription period).
  • Blood pressure meters: Omron M7 Intelli IT Afib (about €130) and Microlife BP B6 (about €120).
  • Solutions which measure the electrical activity of the heart: Apple Watch Series 4 smartwatch or a newer version with ECG feature (starts at about €450), Withings Move ECG (about €130).
  • Solutions which measure blood flow: smart watches/smart bands, for instance Fitbit Versa (starts at about €110) or Apple Watch Series 3 or a newer version (starts at about €230), or mobile applications measuring blood flow on the tip of finger.

Different devices have different benefits, so finding the best possible solution depends on several factors. If a person is already used to regular blood pressure monitoring, the use of a technologically-advanced blood pressure meter may be a good choice. The drawback of this method is the relatively high purchase price of the device. In addition, the device is not as easily portable as the other solutions.

Mobile applications are the cheapest and easiest way of getting oneself a solution for AFib detection. As smartphones have become widespread, almost everyone has a device in their pocket, which is suited for doing measurements. All that the user needs to do is to download a mobile application on the App Store or Google Play Store. After doing this the measurement can be initiated on the application. All collected and measured data are analyzed on the cloud service of the application. The result of the analysis is available immediately. The mobile applications do not enable continuous monitoring. For this reason, it is recommended to take regular measurements, for instance in the morning and in the evening.

The Finnish CardioSignal application utilizes the built-in movement sensors of the smartphone. These sensors measure the micro-movements of the chest caused by the heart. This technique is called gyrocardiography (GCG). Clinical trials have shown that it is an extremely accurate method which enables self-monitoring of heart movements.

There are also mobile applications which utilize photoplethysmogram (PPG). These applications try to estimate the heart functions based on the detection of blood flow. The use of a PPG mobile application requires that the user places his/her fingertip over the camera lens and flashlight and tries to hold the finger steady while pressing for 1-2 minutes. Because peripheral circulation typically deteriorates with age and the measurement is technically demanding, it is a challenging technique for the elderly.

A smartwatch can be constantly worn on a user’s wrist and it is possible to take measurements as needed. However, the purchase price is considerably high and the consumer’s decision to buy is usually not only based on the AFib detection feature but also on other smart features of the device. With regard to smartwatches it is useful to know that their continuous monitoring technique is often based on a rather approximate heart rate monitoring from the user’s wrist utilizing LED light and the PPG technique. For ensuring a successful measurement and for receiving a result the user should preferably be at rest. In addition, the smartwatch band should be tightened properly to ensure close contact with the skin. When the user moves during normal everyday activities these devices cannot reliably estimate the heart rate. This has also been mentioned in the user instructions of the devices. In addition to the PPG technique, some smartwatches provide the user with a single-lead ECG. The user needs to initiate the recording and keep their fingers on a certain part of the device during it.


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What should I do if I have atrial fibrillation?

The diagnosis of atrial fibrillation and treatment decisions are always and solely made by the physician. If you suspect you might have atrial fibrillation, please contact your doctor. A confirmed diagnosis of the atrial fibrillation and any treatment decisions made by the physician are always based on a 12-lead ECG during the arrhythmia. The measurement is done either at the clinic or in the laboratory with an ECG device or with a wearable Holter monitor, which needs to be worn for a few days. Paroxysmal atrial fibrillation is very difficult to verify and the patient’s rhythm has often already returned to normal by the time she/he gets to the ECG recording. It is also possible that no paroxysmal atrial fibrillation episodes occur while wearing the Holter monitor.

To find the right treatment, the patient will be interviewed, a physical examination is carried out and an ECG recording is taken. In addition to this also blood tests, pulmonary imaging, structural heart imaging and stress tests may be carried out as needed. It makes it considerably easier for the doctor if the patient is able to provide a detailed description of her/his symptoms. If possible, it would be useful to go through the following before attending the doctor’s appointment:

  • potential findings of heart monitoring devices used at home
  • how do the symptoms feel, how long do they last, when does the symptom start and when does it disappear?
  • in which situations do the symptoms occur and how often?
  • is the heart rate irregular and how fast is it?

Treatment of atrial fibrillation

The treatment of atrial fibrillation is divided into three separate categories:

  • Prevention of stroke
  • Control of arrhythmia (prevention of arrhythmia vs. heart rate control)
  • Control of underlying diseases and predisposing factors

The prevention of atrial fibrillation focuses on minimizing the risk of thrombosis and on restoring the normal sinus rhythm. An episode of atrial fibrillation can go away on its own or with medication in a few days. If this does not happen, electrical cardioversion for restoring normal heart rhythm may be conducted in brief general anesthesia. If atrial fibrillation has continued over 48 hours, anticoagulant therapy (i.e., blood thinning drugs) will be initiated in addition to electrical cardioversion. Treatment with anticoagulants is continued for one month and it is needed because of an increased risk of thrombosis (the formation of a blood clot within a blood vessel).

In long-term treatment potential underlying diseases of the patient and the severity of atrial fibrillation are taken into account. It is also essential to take care of the predisposing factors, such as high blood pressure and obesity.

Atrial fibrillation tends to recur and over time it may even become permanent. Thus, either rate control or rhythm control can be selected as a treatment strategy. In rate control no attempts are made to restore or maintain normal sinus rhythm and AFib is accepted as a permanent condition. This is often a good option in elderly patients. Rhythm control usually requires the use of antiarrhythmic drugs, and the treatment decision is made individually for each patient.

Because atrial fibrillation tends to recur, attempts are usually made to maintain normal rhythm with medication. Prophylactic drugs will be selected individually for each patient. Treatment with beta blockers can be initiated already in primary care but antiarrhythmic drugs can only be initiated under the guidance of a specialized physician. In the prevention of atrial fibrillation, a properly planned anticoagulant therapy has a positive effect on the prognosis of the patient. When the need for medication is evaluated, a so-called CHA₂DS₂-VASc score is utilized. Either NOACs (apixaban, dabigatran, edoxaban, rivaroxaban) or warfarin can be used for the prevention of thrombosis. It should be noted that aspirin is no longer regarded as a valid drug for reducing stroke risk associated with atrial fibrillation.

What is the CHA₂DS₂-VASc scoring system?

The CHA₂DS₂-VASc scoring system helps in determining the right treatment for a patient suffering from atrial fibrillation. It also aims at evaluating the stroke risk of the patient. It contains many yes–no questions, and each of them will give a score. The structure of the scoring is as follows:

Factor Score
C Congestive heart failure 1
H Hypertension 1
A₂ Age >=75 years 2
D Diabetes mellitus 1
S₂ Prior TIA or stroke 2
V Vascular disease, for instance cardiovascular disease 1
A Age 65-74 years 1
Sc Sex (female), when aged >=75 1

The patient’s total risk score is the sum of all above mentioned factors. Based on this, the need for medication is evaluated as follows:

Total score Treatment
Score 0, small risk No need for medication
Score 1, moderate risk No medication or oral anticoagulant therapy. The physician makes the decision in individually for each patient. The medication might not be given if there is a high risk of bleeding or another risk factor (for instance blood pressure) has been treated well and the patient does not have other minor risk factors (for instance smoking, dyslipidemia or renal failure).
Score 2 or more, high or very high risk Oral anticoagulation therapy is indicated almost without exception.

Living with atrial fibrillation

Atrial fibrillation is a usually a chronic disease and it needs to be monitored regularly. Properly treated it does have any significant effect on the quality of life of the patient: one just needs to learn to get along with it.

Over time paroxysmal atrial fibrillation tends to become permanent. However, this does not happen to everybody and it may take several years. If this happens, meaning that cardioversion or other procedures for restoring normal rhythm are no longer carried out, treatment of atrial fibrillation still continues. In that case the treatment is about selecting the correct medication for the patient. In Finland there are tens of thousands of patients, who have permanent atrial fibrillation and use an anticoagulant therapy. In spite of this they manage to live a rather normal life. Permanent atrial fibrillation may feel uncomfortable at first but the body gets used to it within a couple of months and the symptoms are relieved.

Long-term persistent atrial fibrillation is followed up regularly. The follow-up visits aim at ensuring that the medication and selected treatment are appropriate. The frequency and content of the follow-up visits depend on the patient. For instance, permanent atrial fibrillation tends to slow down with age, and in that case medication given for slowing down the heart rhythm can be reduced to stopped. The follow-up is based on regional chains of care, organized by ambulatory care and specialized care.

You can also manage atrial fibrillation yourself with several ways. Healthy lifestyle plays an important role in this. Do not let atrial fibrillation limit your life: exercise and enjoy healthy food and relationships with your friends and family. Avoid factors which seem to cause you episodes of atrial fibrillation. Predisposing factors of atrial fibrillation include for instance poor sleep, drinking too much alcohol, stress, other illnesses, heavy meals and consuming too much caffeine.

Take care of a healthy lifestyle, remember to relax and sleep well.


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