Atrila fibrillation: a review

Abstract

Atrial fibrillation (AF) is the most common sustained arrhythmia and increases exponentially with age. The physiologic basis are certain triggers initiating multiple micro-reentry circuits, which require a certain amount of "myocardial mass" to be sustained. There are numerous predisposing factors for AF, mostly leading to dilatation or hypertrophy of the atrial myocardium. Lone AF, however, occurs in structurally normal hearts. In the management of AF it is mandatory to decide between medical or electrical cardioversion in persistent AF and rate control in permanent AF. Medical cardioversion or prophylaxis of recurrence can be performed with Class IA, IC or Class III antiarrhythmic drugs. The choice of drugs depends on the underlying cardiac pathology of the individual patient. Patients with long duration of poor rate control during AF are at risk for tachycardia-induced cardiomyopathy. Cardioversion is safe to be performed within 48 hours after the onset of AF without prior and--if there is no risk of recurrence--without consecutive anticoagulation. When AF persists longer than 48 hours, anticoagulation for three weeks is mandatory prior to attempted cardioversion, or alternatively, transesophageal echocardiography can be performed to exclude the presence of an intraatrial thrombus. Anticoagulation has to be maintained for a minimum of four weeks after the restoration of sinus rhythm. Anticoagulation is required for paroxysmal, persistent and permanent AF. Lone atrial fibrillation in patients under the age of 60 years is an exception to these rules and does not require anticoagulation. In case of refractory AF with poor rate control, catheter ablation of the AV node with pacemaker implantation is the treatment of last choice. Early attempts to provide a cure for AF included the surgical "Maze" procedure, followed by linear catheter ablation with the goal of reducing the atrial mass. Catheter ablation of the triggers of AF, which mainly originate at the pulmonary veins and the "substrate modification" have been introduced in the last couple of years and is performed increasingly in specialized EP centers.