Atrial Fibrillation

Atrial fibrillation is the most common sustained arrhythmia encountered in clinical practice. Its incidence increases with age and the presence of structural heart disease.

Atrial fibrillation (AF) is an abnormal heart rhythm characterised by rapid and irregular beating. Often it starts as brief periods of abnormal beating which become longer and possibly constant over time. Most episodes have no symptoms. Occasionally there may be heart palpitations, fainting, lightheadedness, shortness of breath, or chest pain. The disease is associated with an increased risk of heart failure, dementia, and stroke. It is a type of supraventricular tachycardia.

Hypertension and valvular heart disease are the most common alterable risk factors for AF. Other heart-related risk factors include heart failure, coronary artery disease, cardiomyopathy, and congenital heart disease. In the developing world valvular heart disease often occurs as a result of rheumatic fever. Lung-related risk factors include COPD, obesity, and sleep apnea. Other factors include excess alcohol intake, diabetes mellitus, andthyrotoxicosis. However, half of cases are not associated with one of these risks. A diagnosis is made by feeling the pulse and may be confirmed using an electrocardiogram (ECG). A typical ECG in AF shows no P waves and an irregular ventricular rate.

AF is often treated with medications to slow the heart rate to a near normal range (known as rate control) or to convert the rhythm to normal sinus rhythm (known as rhythm control). Electrical cardioversion can also be used to convert AF to a normal sinus rhythm and is often used emergently if the person is unstable. Ablation may prevent recurrence in some people. Depending on the risk of stroke either aspirin or anti-clotting medications such as warfarin or a novel oral anticoagulant may be recommended. While these medications reduce this risk, they increase rates of major bleeding.

Atrial fibrillation is the most common serious abnormal heart rhythm. In Europe and North America, as of 2014, it affects about 2% to 3% of the population. This is an increase from 0.4 to 1% of the population around 2005. In the developing world about 0.6% of males and 0.4% of females are affected. The percentage of people with AF increases with age with 0.14% under 50 years old, 4% between 60 and 70 years old, and 14% over 80 years old being affected. AF and atrial flutter resulted in 112,000 deaths in 2013, up from 29,000 in 1990. The first known report of an irregular pulse was by Jean-Baptiste de Sénac in 1749. This was first documented by ECG in 1909 by Thomas Lewis.

The American College of Cardiology (ACC), American Heart Association (AHA), and the European Society of Cardiology (ESC) recommend in their guidelines the following classification system based on simplicity and clinical relevance. All people with AF are initially in the category called first detected AF. These patients may or may not have had previous undetected episodes. If a first detected episode stops on its own in less than 7 days and then another episode begins, later on, the category changes to paroxysmal AF. Although patients in this category have episodes lasting up to 7 days, in most cases of paroxysmal AF the episodes will stop in less than 24 hours. If the episode lasts for more than 7 days, it is unlikely to stop on its own, and is then known as persistent AF. In this case, cardioversion can be used to stop the episode. If cardioversion is unsuccessful or not attempted and the episode continues for a long time (e.g., a year or more), the patient's AF is then known as permanent.

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