What are the risks of elective DC cardioversion from atrial fibrillation?

There are relatively few recent published data on the risks of elective DC cardioversion. The risks include those relating to an, albeit brief, general anaesthetic which will reflect the overall health of the patient, and those relating to the application of synchronised direct current shock. The latter include the development of bradyarrhythmias (more likely in the presence of heavy beta blockade and especially where there is concomitant use of calcium channel antagonists) and tachyarrhythmias (more
likely in the presence of deranged biochemistry including low serum K+ or Mg++, and high levels of serum digoxin). These dysrhythmias may necessitate emergency pacing or further cardioversion and full resuscitation. Elective cardioversion of adequately assessed patients should only be undertaken by appropriately trained staff in an area where full resuscitation facilities are available. Following cardioversion high quality nursing care and ECG monitoring will be required until the patient has recovered from the anaesthetic and is clinically stable. Failure to observe these guidelines will likely result in higher
complication rates which on occasion includes death.

The other major complication of DC cardioversion is thromboembolism which can be debilitating and is sometimes fatal. There have been no randomised trials of anticoagulation but there is convincing circumstantial evidence that anticoagulation reduces the risk of cardioversion-related thromboembolism from figures in the order of 7% to less than 1%: anticoagulation does not appear to abolish the risk and this should be made explicit when informed consent is obtained from a patient. Patients with recent onset AF are not devoid of the risks of cardioversion-related thromboembolism and also require anticoagulation.