Atrial Fibrillation

Atrial Fibrillation Overview

Atrial Fibrillation (also known as AFib or AF) is the most common abnormal heart rhythm (cardiac arrhythmia) seen in clinical practice and accounts for roughly one-third of all hospital admissions for cardiac rhythm disturbances.^1,6  AFib occurs when the electrical signals in the heart’s upper chambers (atria) beat in an uncoordinated and uncontrolled fashion.  This can cause irregular and oftentimes rapid heart rhythms.  The resulting effect on blood flow within the heart (hemodynamics) significantly increases stroke risk by 4-5 fold, and can lead to other cardiovascular complications such as heart failure.^3,4  The American Heart Association estimates that at least 15-20% of all strokes are caused by AFib.³  Patients with AFib normally experience symptoms such as palpitations, chest pain, shortness of breath, fatigue, lightheadedness, and fainting.¹  If left untreated, AFib can lead to permanent changes in the heart’s structure and function.²   

Three main categories are used to describe types of AFib:^1,9,10

• Paroxysmal AFib – Abnormal rhythm begins suddenly – patients can be converted to normal rhythm with treatment or the abnormal rhythm may resolve on its own (within 48 hours). 
• Persistent AFib – Abnormal rhythm continues until it is converted back to normal rhythm with treatment (can last longer than 7 days).
• Permanent AFib – Abnormal rhythm cannot be converted back to normal rhythm, even with treatment.  By definition, rhythm control interventions are not pursued in these patients. 

Without proper treatment most patients will experience repeated and worsening recurrences of both paroxysmal and persistent AFib.^1,2,9,10  This progression of disease, in the form of irreversible electrical and structural heart damage, ultimately leads the patient to a permanent state of AFib.^2,9  Therefore, it is important to restore normal heart rhythm quickly after the onset of AFib to prevent or slow this progression of worsening disease.² 

Atrial Fibrillation Burden

There are approximately 2.5 million Americans⁵ and 4.5 million Europeans that suffer from AFib.¹  Annual costs related to the management of AFib patients in the US are approximately $7 billion and roughly €13.5 billion in the European Union (estimated at $26 billion in total).^1,7,8  These costs consistently rank AFib as a leading public health expenditure.⁸

Due to an aging population and higher survival rates amongst patients with underlying diseases associated with AFib, it is expected that the number of AFib sufferers will increase 3 fold over the next 50 years.^2,4,8    Based on these figures, AFib, along with congestive heart failure and type 2 diabetes/metabolic syndrome make up the three fastest growing cardiovascular epidemics.⁴  AFib is expected to become one of the leading burdens on the global healthcare system in coming years.⁴ 

Atrial Fibrillation Treatment

The three main treatment goals for AFib are restoring and maintaining a normal heart rhythm, controlling the heart rate, and reducing stroke risk.¹  

Rapid beating of the heart (tachycardia) is a condition often associated with AFib, and may be effectively treated with the use of rate control medications.^1,9,10  Beta-blockers, calcium channel blockers, and digoxin are routinely used to slow down rapid heart rates.^9,10  Additionally, anticoagulants such as warfarin and/or antiplatelets such as aspirin are also routinely used in Afib patients to manage the increased stroke risk.^9,10

However, by restoring and maintaining normal heart rhythm, one can address both conditions.  A heart back in normal rhythm will tend to beat at normal rates, and a normal rhythm also promotes improved blood flow within the heart (hemodynamics), reducing the risk of stroke in that patient.^1,9,10

Two common approaches are used in converting a heart with AFib back to normal heart rhythm.  The first is to use an antiarrhythmic drug for cardioversion, a term describing the restoration of normal heart rhythm.  This is also referred to as chemical or pharmacological cardioversion.  The other common approach is the use of electric shock, also known as direct current (DC) or electrical cardioversion. 

Pharmacological cardioversion agents are generally safe, effective and may be administered conveniently in the outpatient setting.^1,12  Electrical cardioversion, while also safe and effective, requires patient sedation.^11,12  Therefore, with electrical cardioversion, delays in the cardioversion of patients are common due to the required scheduling of facilities, staff and other resources.^11,12 

The rapid cardioversion of AFib after onset is believed to limit the extent of electrical and structural remodeling,  increasing the likelihood of success in restoring and maintaining a normal heart rhythm.^1,2  Pharmacological and electrical cardioversion studies show patients have higher cardioversion success rates when AFib has been present for less than 24 hours.¹  While patients with AFib of longer duration can be cardioverted, cardioversion success rates decline as duration of AF increases.¹

Following successful pharmacological or electrical cardioversion, oral antiarrhythmic medications are typically prescribed to maintain normal heart rhythm and prevent future recurrences of AFib.^1,9,10  In certain groups of patients, surgical procedures, such as catheter ablation and pacemaker implantation, may be alternative options for the long term maintenance of a normal heart rhythm.^9,10