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Key Concepts

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  • Epidemiology

    • Atrial fibrillation (AF) affects about 2 percent of the general population. It is strongly correlated to age and the prevalence increases to 10 to 15 percent in patients over the age of 80. It is associated with hypertension, heart failure, valvular heart disease, and ischemic heart disease. In 10 to 15 percent there is no underlying cardiac pathology present (lone AF).

  • Pathophysiology

    • AF requires both an initiating event and a permissive atrial substrate. While automaticity and triggered activation is often, but not exclusively, found within and around the pulmonary veins and is involved in AF initiation, different mechanisms of reentry in both atria also play an important role in sustaining AF. As the atrial size increases, the conduction velocity slows or the atrial refractory period decreases, and the probability of initiating and sustaining AF increases.

  • Clinical features

    • Besides symptoms, hemodynamic compromise, and tachycardia-induced cardiomyopathy, stroke remains the most feared complication. AF accounts for about 25 percent of strokes in patients older than 80 years and increases a person’s risk of stroke by 5-fold.

  • Diagnostics

    • A transthoracic and transesophageal echocardiogram should determine left atrial diameter and evaluate for the presence of a left atrial thrombus. A cardiac catheterization will provide information about the presence of coronary artery disease and the anatomical location of the circumflex coronary artery. In patients who have failed catheter ablation, chest computerized tomography (CT) is indicated to assess for pulmonary vein stenosis.

  • Treatment

    • The surgical procedures currently performed to ablate AF include the biatrial Cox-Maze procedure (CMP), left atrial lesion sets, and pulmonary vein isolation. All of these operations have been simplified by alternative energy sources.

  • Outcome

    • Success rates vary and depend on the lesion set performed, the energy source used, the type of AF, and the presence of concomitant pathology. The biatrial CMP has an approximately 90 percent success rate for all types of AF and has set the benchmark for alternative lesion sets as well as for new and less invasive approaches currently under development.

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Introduction

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Atrial fibrillation (AF) is the most common sustained arrhythmia worldwide with an increasing incidence with age. Adults at the age of 40 years have a 25 percent risk of developing AF during their lives.1 The actual incidence and prevalence of AF is likely underestimated due to undetected asymptomatic occurrences or patients ignoring paroxysmal episodes. Experts predict that the number of AF-related hospitalizations will increase and almost double to 3.5 million by the year 2025 in the United States.

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Although AF itself is not considered a life-threatening arrhythmia, it is associated with significant morbidity and mortality secondary to hemodynamic compromise and tachycardia-induced cardiomyopathy in some patients. Besides palpitations resulting in discomfort and anxiety, the loss of synchronous atrioventricular contractility may cause various degrees of ventricular dysfunction, exercise intolerance or congestive heart failure in patients with AF. Furthermore, stasis of blood flow in the fibrillating left atrium increases the risk ...

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