69 What are the risks of elective DC cardioversion
from atrial fibrillation?
Suzanna Hardman and Martin Cowie
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 anti-
coagulation reduces the risk of cardioversion-related thrombo-
embolism 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.
FFuurrtthheerr rreeaaddiinngg
Bjerkelund CJ, Orning OM. The efficacy of anticoagulant therapy in
preventing embolism related to DC electrical cardioversion of atrial
fibrillation. Am J Cardiol1969; 2233 : 208–16.