Atrial fibrillation (AF) can be found in an increasing number of cardiac surgical patients due to a higher patient's age and comorbidities. Atrial fibrillation is known, however, to be a risk factor for a greater mortality, and one aim of intraoperative AF treatment is to approximate early and long-term survival of AF patients to survival of patients with preoperative sinus rhythm. Today, surgeons are more and more able to perform less complex, that is, minimally invasive cardiac surgical procedures. The evolution of alternative ablation technologies using different energy sources has revolutionized the surgical therapy of atrial fibrillation and allows adding the ablation therapy without adding significant risk. Thus, the surgical treatment of atrial fibrillation in combination with the cardiac surgery procedure allows to improve the postoperative long-term survival and to reduce permanent anticoagulation in these patients. This paper focuses on the variety of incisions, lesion sets, and surgical techniques, as well as energy modalities and results of AF ablation and also summarizes future trends and current devices in use. 1. Background Atrial fibrillation is defined as uncontrolled atrial electrical excitation at a rate of >300 beats per minute. The conduction to the ventricles is irregular and in variable frequencies, therefore resulting in the types of slow (bradycardiac), normofrequent, or fast (tachycardiac) atrial fibrillation (AF). Furthermore, AF can be divided into paroxysmal, persistent, and permanent (accepted) AF . Paroxysmal AF is self-terminating, usually within 48 hours. Although AF paroxysms may continue for up to 7 days, after 48 hours the likelihood of spontaneous conversion is low, and anticoagulation must be considered. Persistent AF is an AF episode which either lasts longer than 7 days or requires termination by cardioversion with drugs or by direct electrical cardioversion. The persistent types of AF are frequently symptomatic and are, depending on the comorbidities, associated with an increased stroke risk. Persistent AF is added by the subtype of long-standing persistent AF (>1y), when it is decided to adopt a rhythm control strategy. Permanent AF is when the presence of the arrhythmia is accepted and a rhythm control is no longer pursued. Surgical treatment of atrial fibrillation should be considered as a stand-alone concept when patients do not get free of AF or symptoms despite multiple interventional ablations or when a contraindication for catheter ablation exists . Furthermore, atrial fibrillation as a comorbidity
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