Atrial Stunning Following Sinus Rhythm Restoration: Which Mechanism, Time Course and Implication for Anticoagulation?

Atrial fibrillation (AF) is one of the most common types of arrhythmia, occurring in up to 4% of patients over 60 years of age [1–3]. Cardioversion is performed in patients with AF in an effort to improve cardiac function, relieve symptoms, and decrease the risk of thrombus formation. Successful cardioversion is associated with a 5%–7% incidence of embolism among patients who have not received adequate anticoagulant therapy [4–9]. In fact, the cardioversion of AF to sinus rhythm is associated with transient mechanical dysfunction of the left atrium (LA) and left atrial appendage (LAA) and the development of spontaneous echocardiographic contrast. This phenomenon has been termed “stunning” and is considered an important factor for thromboembolic stroke following cardioversion of AF to sinus rhythm [10–15].