Atrial stunning after cardioversion

Atrial stunning after cardioversion

Atrial stunning denotes the delay in the onset of organised atrial contraction after a successful cardioversion of atrial fibrillation. Since thrombus formation is more likely in the left atrial appendage, stunning of the left atrial appendage is thought to be responsible for the increased risk of thromboembolism after a successful cardioversion. This occurs regardless of whether it was electrical cardioversion or pharmacological cardioversion. Stunning can also be there after spontaneous correction of atrial fibrillation. Left atrial appendage emptying velocity is low in atrial stunning. Left atrial appendage emptying velocity can be measured by transthoracic or transesophageal Doppler echocardiography.

The stunning is maximum soon after cardioversion and atrial mechanical function gradually improves over a course of days to weeks. The speed of recovery of mechanical function may depend on the duration of atrial fibrillation prior to cardioversion. 80% or more episodes of thromboembolism occur within the first three days and it is relatively rare after 10 days. Hence anticoagulation is recommended during cardioversion of atrial fibrillation in all patients in whom atrial fibrillation has lasted more than 48 hours. The risk of thromboembolism associated with cardioversion is low in patients with AF duration of less than 48 hours [1]. Anticoagulation is also recommended when the duration of atrial fibrillation is unknown.

Reference

  1. Alastair J Rankin, Stephen H Rankin. Cardioverting acute atrial fibrillation and the risk of thromboembolism: not all patients are created equal. Clin Med (Lond). 2017 Oct;17(5):419-423.