electrical cardioversion in atrial fibrillation
DC cardioversion requires a light general anaesthetic or sedation with intravenous diazepam; intubation is not usually required.
- the DC shock is synchronized with an R wave on the electrocardiogram in order to reduce the chance of ventricular fibrillation
- presence of two or more consecutive P waves after shock delivery is usually considered as an indication of successful DCC (1)
DC cardioversion may precipitate systemic emboli from intracardiac thrombus. To avoid thromboembolic events:
- formal anticoagulation is required for at least three weeks before and four weeks after the cardioversion since
- thrombi may form as soon as 48 hours after the onset of AF(2)
- co-ordinated atrial activity may not resume for 2 weeks following cardioversion even if sinus rhythm is apparent on the ECG
- prolonged anticoagulation is not needed when the arrhythmia has existed for less than 48 hours
- no intracardiac thrombus is apparent on trans-oesophageal echocardiography (3)
The use of DC cardioversion is
- recommended acutely in patients who are haemodynamically unstable
- considered electively in order to initiate a long-term rhythm control management strategy (1)
In patients who are haemodynamically stable and do not have severe underlying heart disease, outpatient/ambulatory DCC can be carried out (1)
The results of DC cardioversion in patients with chronic atrial fibrillation indicate a high initial effectiveness but poor long-term effectiveness:
- 70-90% patients with chronic atrial fibrillation will be converted to sinus rhythm by DC cardioversion
- 60-75% of successfully cardioverted patients will revert to atrial fibrillation within one year
NICE state with respect to cardioversion (6)
- for people having cardioversion for atrial fibrillation that has persisted for longer than 48 hours, offer electrical (rather than pharmacological) cardioversion
- consider amiodarone therapy starting 4 weeks before and continuing for up to 12 months after electrical cardioversion to maintain sinus rhythm, and discuss the benefits and risks of amiodarone with the person.
- for people with atrial fibrillation of greater than 48 hours' duration,
in whom elective cardioversion is indicated
- both transoesophageal echocardiography (TOE)-guided cardioversion and conventional cardioversion should be considered equally effective
- a TOE-guided cardioversion strategy should be considered:
- where experienced staff and appropriate facilities are available and
- where a minimal period of precardioversion anticoagulation is indicated
due to the person's choice or bleeding risks
- in people with atrial fibrillation in whom the duration of the arrhythmia is greater than 48 hours or uncertain and considered for long-term rhythm control, delay cardioversion until they have been maintained on therapeutic anticoagulation for a minimum of 3 weeks
- during this period offer rate control as appropriate
- DCC is contraindicated in patients with digitalis toxicity (1)
- maintaining sinus rhythm after cardioversion
- several class IA, IC and III drugs are effective in maintaining sinus rhythm but increase adverse events, including pro-arrhythmia, and disopyramide and quinidine are associated with increased mortality. The authors of a systematic review concluded that (5) any benefit on clinically relevant outcomes (embolisms, heart failure, mortality) remains to be established
- (1) European Heart Rhythm Association et al.Guidelines for the management of atrial fibrillation: the Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC). Eur Heart J. 2010 (19):2369-429.
- (2) Gutierrez C, Blanchard DG.Atrial fibrillation: diagnosis and treatment. Am Fam Physician. 2011;83(1):61-8.
- (3) Lafuente-Lafuente C, Mahé I, Extramiana F.Management of atrial fibrillation. BMJ. 2009;339:b5216.
- (4) Lip GYH, Watson RDS, Singh S. Cardioversion of atrial fibrillation. BMJ 1996;312: 112-5.
- (5) Lafuente-Lafuente C et al. Antiarrhythmics for maintaining sinus rhythm after cardioversion of atrial fibrillation.Cochrane Database Syst Rev. 2007 Oct 17;(4):CD005049
- (6) NICE (April 2021). Atrial fibrillation: the management of atrial fibrillation
Last edited 05/2021 and last reviewed 05/2021