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cardioversion

Indications: - supraventricular tachycardia - atrial fibrillation, atrial flutter Management: 1) see defibrillation for ventricular tachycardia & ventricular fibrillation 2) cardioversion for atrial fibrillation/flutter a) DC cardioversion (50, 100, 200, 300, 360 joules) - synchronized transthoracic DC cardioversion [2] - 67-100% efficiency - ibutilide IV prior to cardioversion decreases energy required for cardioversion - risks - anesthetic - ventricular fibrillation from poor synchronization - transvenous electrical cardioversion [2] - useful when transthoracic cardioversion has failed - usually shock between electrodes in right atrium & coronary sinus & or indifferent electrodes on the back - low energies often effective - monophasic defibrillator: 360 J single shock - DC cardioversion more effective than chemical cardioversion [3] b) chemical cardioversion - pharmacologic agents - class 1A, 1C or 3 antiarrhythmic agents - conversion & maintenance of sinus rhythm c) indications - patient is unstable - mitral stenosis - mitral regurgitation - new onset of atrial fibrillation within 48 hours d) anticoagulation for patients with long-term AF* - 3 weeks prior to elective cardioversion - 4 weeks after successful cardioversion - edoxaban as safe & effective as enoxaparin-warfarin [4] - cardioversion may itself not cause thromboembolism [5] e) antiarrhythmic therapy for maintenance of sinus rhythm - may or may not be needed - amiodarone (most commonly used) - 400 mg for 30 days, then 200 mg QD - especially useful with structural heart disease - if no structural heart disease - flecainide 100 mg BID, or - propafenone 150-225 mg TID - 30-50% of patients will maintain sinus rhythm after 1-2 years Notes: - since atrial fibrillation usually involves the left atrium, elective attempts at chemical or electrical cardioversion should be preceded by anticoagulation therapy of at least 3 weeks duration to minimize the risk of systemic embolization upon restoration of sinus rhythm - alternatively, atrial thrombi may be excluded by transesophageal echocardiogram - following conversion to sinus rhythm, type Ia antiarrhythmic agents (quinidine, procainamide) or type III antiarrhythmic agents (amiodarone, sotalol) can be used in an effort to sustain sinus rhythm - because atrial contractility may take up to a month to recover (atrial stunning), it is recommended to continue anticoagulation for 4 weeks after successful cardioversion

Specific

chemical cardioversion defibrillation (electrical cardioversion, automated external difibrillation, AED) synchronized cardioversion

General

clinical procedure

References

  1. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 238-40
  2. Feliciano, Z. In: UCLA Intensive Course in Geriatric Medicine & Board Review, Marina Del Ray, CA, Sept 12-15, 2001
  3. Bellone A et al. Cardioversion of acute atrial fibrillation in the emergency department: A prospective randomised trial. Emerg Med J 2012 Mar; 29:188. PMID: 21422032
  4. Goette A, Merino JL, Ezekowitz MD et al. Edoxaban versus enoxaparin-warfarin in patients undergoing cardioversion of atrial fibrillation (ENSURE-AF): A randomised, open-label, phase 3b trial. Lancet 2016 Aug 30; [e-pub]. PMID: 27590218 http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(16)31474-X/fulltext - Briasoulis A, Afonso L Do NOACs ENSURE safe cardioversion in atrial fibrillation? Lancet 2016 Aug 30 PMID: 27590222 http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(16)31410-6/fulltext
  5. McIntyre WF, Connolly SJ, Wang J et al. Thromboembolic events around the time of cardioversion for atrial fibrillation in patients receiving antiplatelet treatment in the ACTIVE trials. Eur Heart J 2019 Aug 4 PMID: 31377776 https://academic.oup.com/eurheartj/article/40/36/3026/5543556