Atrial Fibrillation – Causes,Diagnosis,Treatment & FAQs

What Is Atrial Fibrillation (AF)?

Atrial fibrillation, also known as AF is a rhythm disturbance of heart where it beats irregularly.

The main risk for this condition is that it can cause blood to clot and cause Stroke.

Let us try to understand, what happens during Atrial Fibrillation.

The heart will usually beat following a regular rhythm.

This sinus node which is the pacemaker of the heart discharges electricity at a regular interval which leads the heart to beat in regular rhythm.

In Atrial Fibrillation the natural pacemaker of the heart does not work efficiently anymore.

Therefore instead of regular electrical discharges from the sinus node, there happens to be electrical impulses originating from all over the atrium (upper chambers of heart) in an irregular fashion; thus resulting in the heart to beat irregularly.

The main risk of this condition is that it causes blood to clot within the heart.

This clot can then break away when the heart pumps to various parts of the body and cause occlusion of blood vessels in major organs thus causing irreversible structural and functional damage.

The main risk is for the clot to go the brain and cause strokes. The risk of Stroke from Atrial fibrillation can vary from person to person and increases with age.

Other medical co morbidities like Hypertension (Blood Pressure), heart failure, Diabetes also increases this risk.

 

How Is Atrial Fibrillation Classified?

Atrial Fibrillation can be classified or described in two ways.

  • Valvular or Nonvalvular: This classification describes whether the heart valves are abnormal (due to causes like rheumatic fever, leaky heart valve, heart valve replacement etc.) and whether this is the causative factor for AF.
  • Paroxysmal or Persistent AF: If the heart rhythm is always irregular it is described as persistent AF. If the heart rhythm goes irregular for a period of time, but then returns to normal it is called paroxysmal AF.

 

What Causes Atrial Fibrillation (AF)?

Abnormalities or any kind of damage to the structure of the heart is one of the most common causes of atrial fibrillation.

Some of the possible causes of atrial fibrillation are:

  • Coronary artery diseases.
  • Heart attack
  • High blood pressure
  • Abnormal heart valves (often due to rheumatic fever in childhood)
  • Any congenital heart defects.
  • An overactive thyroid gland or any other kind of metabolic imbalance.
  • Previous heart surgery.
  • Any kind of viral infection.
  • Surgery related stress, other illnesses or pneumonia.
  • Sleep apnoea.

There are people, who suffer from atrial fibrillation but they do not have any defects in THE heart or any kind of damage. This is called Idiopathic Atrial Fibrillation.

What Are The Risk Factors For Atrial Fibrillation?

Some of the risk factors of atrial fibrillation are:

  • Heart disease: Anyone who suffers from a heart condition, like heart valve problems, congenital heart conditions, coronary artery disease, congestive failure in the heart, or history of heart surgery or heart attack, has a greater risk of suffering from atrial fibrillation.
  • Age: Older people have greater risks of atrial fibrillation.
  • High blood pressure: When we suffer from high blood pressure and we fail to control it with changes in lifestyle or medications, we have greater risks of suffering from atrial fibrillation.
  • Other chronic conditions: People, who suffer from certain chronic conditions like overactive thyroid, metabolic syndrome, sleep apnoea, chronic kidney disease, diabetes etc., again have greater risks of atrial fibrillation.

What is the Diagnosis For Atrial Fibrilation?

Diagnosis of Atrial Fibrillation depends on examination of the pulse and cardiovascular system. An ECG is confirmatory of Atrial Fibrillation.

In paroxysmal Atrial Fibrillation a single ECG may not capture the abnormal rhythm and a more prolonged cardiac monitor (Holter) may be needed to capture the heart rhythm at the point where it became irregular.

 

What Investigations Are Done To Diagnose Atrial Fibrillation?

The doctor will recommend several tests to diagnose AF and also to look for causes.

  • ECG: This should be confirmatory for persistent AF
  • Holter monitoring: This is needed for diagnosis of paroxysmal AF.
  • Echocardiogram: This can tell us whether there is any abnormal heart valves; i.e. whether the AF is valvular or non valvular.
  • Blood tests: Thyroid blood tests and electrolytes like sodium, potassium, calcium and Magnesium are usually checked as abnormalities in these levels can precipitate AF.
  • EP studies: In advanced Cardiac centres electrophysiological studies are undertaken. This gives information on the electrical pathways in the heart and aims to diagnose the abnormal pathways that are discharging irregularly to make the heart beat irregularly.

What is The Best Treatment For Atrial Fibrillation?

The treatment of AF has three major aims:

  1. Rhythm Control: this treatment aims to change the heart rhythm back to normal rhythm (sinus rhythm). This is done by a procedure called cardioversion. Cardioversion can be done either by electrical stimulation or by chemical (drugs) agents.
    • Electrical cardioversion: this is done by applying an electrical shock to the heart to stop its abnormal activity. The theory is that the heart’s natural pacemaker will then then take charge and reset itself back to a regular rhythm.
    • Chemical cardioversion: There are drugs which can stop the irregular rhythm and let the natural pacemaker take charge. The common drugs used for this purpose are Amiodarone, Flecainide & Propafenone.
  2. Rate Control: If it is not possible to keep the heart in regular sinus rhythm, then the aim is changed to let the heart beat irregularly but control the rate at which it beats. Drugs commonly used for this are beta blockers (bisoprolol, sotalol), Calcium channel blockers (verapamil, diltiazem) and Digoxin.
  3. Stroke prevention: This aims to keep the blood thin so that it does not clot in the heart and therefore reduces the risk of stroke. The drugs used for this are as follows.
    • Vitamin K Antagonists: These are the oldest class of blood thinners still in use. Warfarin and Sinthrome are two commonest agents. They can be used in all forms of AF and also in conditions where the AF is associated with metallic heart valve replacements. They need regular blood testing and has an antidote.
    • DOAC: These are a new class of drugs called “Direct Oral Anticoagulant”. Agents licenced for use in Stroke prevention from AF include Apixaban, Rivaroxaban, Dabigatran and Edoxaban. They are not licensed to be used in Valvular AF (where the AF is associated with an abnormal heart valve) or in AF associated with metallic heart valve replacement. They do not need regular blood testing but not all them has an antidote.

FAQs

 

1.Can Atrial Fibrillation(AF) Cause a Heart Attack?

Ans: Absolutely not. Atrial Fibrillation is a disorder of the electrical system of the heart resulting in an abnormal and irregular rhythm of the heart.

Heart attack is caused by a clot blocking of a blood vessel and circulation in the heart. They are essentially disorders of two different systems of the heart.

 

2. Is Atrial Fibrillation(AF) Curable?

Ans: In some cases it is possible to reverse the irregular rhythm of the heart in AF to a normal rhythm called sinus rhythm.

This can be done either by delivering a controlled electric shock to the heart or by certain medicines of the antiarrhythmic class.

However it is much more difficult to keep the heart in the normal rhythm in these cases.

A vast majority will just revert back to AF after some time.

Several factors determine whether the AF rhythm can be reversed and kept in normal sinus rhythm.

Age, absence of ischaemic heart disease and a structurally normal heart (as confirmed by echocardiogram) are some of the key factors.

Another interesting option could be doing electrophysiological (EP) studies on the heart’s intrinsic electrical circuit.

In certain cases there are abnormal pathways or tracts carrying the abnormal electric circuit leading to AF.

The EP studies can identify those tracts if present. One potential treatment option will be to ablate that pathway via laser ablation and other methods.

However this may lead to a need for permanent pacemaker implantation in the aftermath.

3. Is AF Life Threatening?

Ans:Usually AF itself is not life threatening.

On certain occasions AF can make the heart go very fast leading to concerning symptoms.

However this can be relatively comfortably controlled by medication or delivering a controlled electrical shock to the heart.

The most concerning feature of AF is however the risk of brain stroke that it confers.

In AF blood does not circulate well inside the heart leading to formation of clot inside the heart.

Eventually when the heart contracts these clots are showered out of the heart thereby blocking any blood vessel that they go in.

Most commonly they travel up the neck blood vessels into the brain and blocks of one of the major brain blood vessels causing large strokes.

This is the most life threatening complication of AF.

 

4. What Are AF Symptoms?

Ans: Most commonly AF is actually asymptomatic i.e. it gives no symptoms.

Hence it remains impossible for the patient to know that the heart is going irregular and take adequate precautions.

Quite often AF is discovered once it has striked the fatal blow in the form of a major brain stroke.

In a small proportion of cases, mainly younger ones, AF may present with some symptoms which include shortness of breath, chest pain and palpitations.

5. How is AF managed?

Ans: There are two strategies to manage AF.

  • The rhythm control strategy aims to reverse the heart rhythm to normal and keep it at a normal rhythm. This can be achieved by delivering a controlled shock to the heart or by using a class of medication called antiarrhythmics. Almost in all cases whatever the method used to reverse the abnormal rhythm of AF, patients will need to stay on an antiarrhythmic drug to keep it in a normal rhythm. Several factors determine whether the AF rhythm can be reversed and kept in normal sinus rhythm. Age, absence of ischaemic heart disease and a structurally normal heart (as confirmed by echocardiogram) are some of the key factors.
  • Electrophysiological studies can identify any abnormal tract within the heart that is carrying the abnormal circuit leading to AF. if present and identified the tract can be destroyed using various methods including laser ablation. Most cases will need a permanent pacemaker inserted following this procedure.
  • The rate control strategy accepts that it will not be possible to either reverse or keep the heart rhythm in normal sinus rhythm. Very often that is the case in a vast majority of patients. Due to various factors the heart rhythm does not reverse, or even if it does so, quickly reverts back to AF. The rate control strategy allows the heart to stay in AF but uses various medication to keep the heart rate under control.
  • Anticoagulation: Whatever the method used to manage AF, anticoagulation medication use is the single most important treatment intervention. Anticoagulation medications are indicated and should be considered even though the heart reverses to normal rhythm via a rhythm control strategy. These are blood thinning medications to try and prevent the most fatal complication of AF, brain stroke. Warfarin (or other vitamin K agonists like Sinthrome) is the oldest agent in use. In recent times some newer anticoagulants have entered the market which are equally effective as warfarin. These include Dabigatran (pradaxa), Rivaroxaban (xarelto), Apixaban (eliquis) and Edoxaban. Being strong blood thinning medication they all carry varying degree of risk towards brain bleeding or other internal bleeding.

 

There are 5 major medical trials which showed that rate control and rhythm control strategies are both equally effective in managing AF; however anticoagulation is of paramount importance whatever strategy you choose.

6. What Is The Life Expectancy with AF?

Ans:Patients with AF if managed appropriately with rate or rhythm control strategies and adequately anticoagulated should have a normal life expectancy.

7. Can AF Cause Shortness of Breath?

Ans:In certain cases where the heart tends to race or beat very fast in AF it can cause some symptoms like shortness of breath, chest pain and palpitations.

8. Does Atrial Fibrillation (AF) Cause High Blood Pressure?

Ans:There is no relation between high blood pressure and AF.

Dr. Dwaipayan Sen


FRCP(Glasgow) MRCP Geriatrics, Clinical Lead Comprehensive Stroke Services, Manchester Centre for Clinical Neurosciences

Dr. Dwaipayan Sen is a Consultant Stroke Physician and Clinical Lead for Comprehensive Stroke Services (Salford Hope Hospital, UK)

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