Since the late 1990s, it has been recognized that the initiation of AF can occur because of premature atrial contractions triggered by beats that arise from the pulmonary veins (PVs), usually from muscular tissue sleeves near the junction with the left atrium. The pathogenesis of AF can be broadly divided into the categories of triggers, substrate, and sustaining mechanisms. Genetic studies have identified specific associations, particularly in the cases of familial AF 4 Achieving a complete understanding of AF is limited by the complexity of this disorder and the heterogeneous patient population it affects. Considerable research has been devoted to the mechanisms and pathogenesis of AF. Disease states commonly associated with AF include hypertension, valvular heart disease, CHF, coronary artery disease, Wolff-Parkinson-White syndrome, pericarditis, obstructive sleep apnea, and cardiomyopathy. 3 The growing prevalence of AF may be influenced by extended survival outcomes for patients with congestive heart failure (CHF), valvular heart disease, and coronary artery disease as AF is common among patients with other forms of structural heart disease.Ītrial fibrillation may be acutely associated with physiologic stressors such as surgical procedures, pulmonary embolism, chronic lung diseases, hyperthyroidism, and alcohol ingestion. The prevalence of A fib increases with age, afflicting about 10% of the population by 80 years of age. An estimated 2.7 to 6.1 million people in the United States have Atrial fibrillation with projections to reach nearly 12.1 million in 2030. Atrial fibrillation is commonly associated with other supraventricular arrhythmias, namely atrial flutter and focal atrial tachycardia.Ītrial fibrillation is the most common sustained cardiac tachyarrhythmia encountered by clinicians worldwide. These classifications are relevant clinically with respect to outcomes and prognosis with rhythm-controlling treatment strategies. These AF classifications are not mutually exclusive and it is common for patients with one type of AF to exhibit overlapping features of another type. Permanent AF refers to AF that persists despite treatment to restore normal sinus rhythm or that is not treated. Long-standing persistent AF refers to patients who have uninterrupted AF for more than a year. 1 Persistent AF refers AF that occurs for longer than 7 days and ends spontaneously or with treatment.
Paroxysmal AF refers to AF that begins suddenly and ends spontaneously within 7 days of onset. The arrhythmia also results in ineffectual atrial contractions affecting cardiac output and vulnerability to blood clot (thrombus) formation that can result in stroke events.Īccording to the 2014 American Heart Association (AHA)/American College of Cardiology (ACC)/Heart Rhythm Society (HRS) clinical practice guidelines, AF can be classified based on the duration of episodes. The disrupted rhythm occurs because of the unpredictable conduction of disordered impulses across the electrical bridge, called the atrioventricular (AV) node, to the lower cardiac chambers (ventricles). The resulting arrhythmia is often rapid and irregular with no discernible pattern (known as irregularly irregular). Atrial fibrillation (AF) is a common heart rhythm disorder caused by degeneration of the electrical impulses in the upper cardiac chambers (atria) resulting in a change from an organized heart rhythm to a rapid, chaotic rhythm.
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