Atrial fibrillation: DC cardioversion: anticoagulation reduced embolic events.

Clinical bottom line (level 4)

Patients with atrial fibrillation who underwent DC cardioversion and were anticoagulated, were less likely to have subsequent embolic events than those who were not anticoagulated (NNT = 23 at 3 days) .

Bjerkelund and Orning: American Journal of Cardiology 1969; 23: 208-216

Expires November 2003

The study

Retrospective cohort study with ?objective ?blinded outcomes, not adjusted for confounding factors, not validated in an independent set of patients.
Setting: acute hospital, Norway

437 patients (aged mean 52 years, 55% female) chronic atrial fibrillation, flutter or tachycardia undergoing DC cardioversion
Control Group: (n = 209, 209 analysed): patients not anticoagulated were not started on anticoagulation before cardioversion
Experimental Group: (n = 228, 228 analysed): patients already anticoagulated continued on this

100% followed for 3 days
Outcome notes:

embolic episode : clinical stroke, lower limb infarction, mesenteric infarction

The evidence

Outcome	Time to outcome	CER	EER	RRR (95% CI)	ARR (95% CI)	NNT (95% CI)
embolic episode	3 days	11 (5.26%)	2 (0.88%)	83% (26% to 96%)	4.39% (1.13% to 7.65%)	23 (13 to 89)

79% of cardioversions were successful.

Comments

Control group patients were younger and more were women. In addition Group I had a worse prognosis having larger hearts, more mitral valve disease, more previous emboli and a worse functional status.
The biases in this study would tend to mask any anticoagulation effect as the 'treatment group' has a worse prognosis.

Citation

Bjerkelund CJ, and Orning OM: The efficacy of anticoagulant therapy for preventing embolism related to DC electrical conversion of atrial fibrillation. American Journal of Cardiology 1969; 23: 208-216

Contributor: Nick Shenker and Chris Ball, November 2000
Reviewer:

_{Clinical Question.}

_Patient	_{chronic atrial fibrillation and DC cardioversion}
_{Intervention or Exposure}	_{anticoagulation}
_Comparison	_{no anticoagulation}
_Outcome	_{subsequent embolic events}