Atrial fibrillation: chronic: internal cardioversion was more effective than external.

Clinical bottom line (level 1b)

  1. Patients with chronic atrial fibrillation who underwent cardioversion were more likely to revert to sinus rhythm if the cardioversion was internal rather than external (NNT = 4 at 10 minutes) .
Levy et al: Circulation 1992; 86 (5): 1415-1420
Expires November 2003

The study

?blinded ?concealed randomised trial with intention-to-treat
Setting: two university hospitals, France and USA

112 patients (aged mean 63 years, 63% male) with
  • chronic AF = 1 month in duration, documented on serial ECG one month apart or by 24 hour ECG
  • failure of AF to convert to sinus rhythm after at least one drug trial with quinidine, procainamide, disopyramide or amiodarone


Excluded if
  • history of amiodarone toxicity or other contraindication to amiodarone


    • Note:
  • All patients had four weeks of amiodarone (400 mg daily for 1 week, followed by 200 mg daily for 5 to 7 days per week), before randomisation.


    • Control Group: (n = 57, 57 analysed): external cardioversion: defibrillator paddles positioned over ventricular apex and right infraclavicular area: 300 J synchronised shock applied; repeated at 360 J if unsuccessful.
    Experimental Group: (n = 55, 55 analysed): internal cardioversion: via femoral vein catheter with tip in tricuspid annulus and most prominent electrode in the right atrium: 200 J synchronised shock applied; repeated at 300 J if unsuccessful
    Patients were anticoagulated before cardioversion (warfarin for 4 weeks before cardioversion, stopped 3 days before, then restarted for 4 weeks in USA; heparin for 3 days in France). Patients had warfarin or aspirin for at least 3 months in patients who achieved sinus rhythm, and indefinitely in patients who remained in AF.
    100% followed for 10 minutes

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    failed cardioversion 10 minutes 19
    (33.3%)    		 5
    (9.09%)    		 73%
    (32% to 89%)    		 24.2%
    (9.84% to 38.7%)    		 4
    (3 to 10)

    Comments

    1. Patients who did not revert to sinus rhythm after 10 minutes then received the alternate form of cardioversion making meaningful long-term follow-up impossible.

    Citation

    1. Levy S, Lauribe P, Dolla E, et al: A randomized comparison of external and internal cardioversion of chronic atrial fibrillation. Circulation 1992; 86 (5): 1415-1420
    Contributor: Chris Ball and Clare Wotton, November 2000
    Reviewer:

    Clinical Question.
    Patient chronic AF
    Intervention or Exposure internal cardioversion
    Comparison external cardioversion
    Outcome reversion to sinus rhythm