Electrical cardioversion for atrial fibrillation

Synchronised direct current (DC) electrical cardioversion is highly effective at restoring sinus rhythm in patients with atrial fibrillation. It has a low complication rate; however, the patient requires procedural sedation while undergoing cardioversion—seek advice from an experienced clinician.

Pretreatment with an antiarrhythmic drug can improve success rates of electrical cardioversion—see Pharmacological cardioversion for dosages.

Biphasic defibrillators are more effective than monophasic waveforms, and the anterior–posterior pad positions appear more effective than the anterolateral positions. Starting with higher energy (150 to 200 joules with a biphasic defibrillator) can improve the success rate of electrical cardioversion and lessen the need for repeat shocks.

Electrical cardioversion has an inherent risk of causing thromboembolic events, such as stroke. To significantly reduce that risk, immediately start anticoagulant therapy in patients not already therapeutically anticoagulated. If atrial fibrillation has persisted for less than 48 hours, electrical cardioversion can be performed without delay. If atrial fibrillation has persisted for longer than 48 hours, or if the duration is unknown, cardioversion should be deferred until the patient has had a minimum of 3 weeks of anticoagulant therapy, unless transoesophageal echocardiography (TOE) has ruled out atrial thrombusJanuary, 2019National Institute for Health and Care Excellence (NICE), 2021.

For anticoagulation before electrical cardioversion, use unfractionated heparin (UFH), low molecular weight heparin (LMWH) or direct-acting oral anticoagulants (DOACs). Follow a local protocol for dosing of anticoagulants for electrical cardioversion, or, if a local protocol is unavailable, see direct-acting oral anticoagulants to prevent thromboembolic events in atrial fibrillation, or parenteral anticoagulants for VTE treatmentJanuary, 2019.

Anticoagulant therapy should be used for at least 4 weeks following electrical cardioversion; see Anticoagulant therapy to prevent thromboembolic events in atrial fibrillation for dosages.