Atrial fibrillation: transoesophageal echocardiography before DC cardioversion allowed earlier cardioversion.

Clinical bottom line (level 1b-)

  1. Patients with atrial fibrillation who had transoesophageal echocardiography looking for atrial thrombus before DC cardioversion were not clearly less likely to have embolic events or be in sinus rhythm at 4 weeks.
  2. Patients who had transoesophageal ECG before cardioversion, were more likely to be successfully cardioverted (NNT = 6 at minutes) .
  3. There was no clear difference in sinus rhythm at 4 weeks.
  4. Patients who had transoesophageal echocardiography had cardioversion sooner than those who did not (mean of 4 weeks).
Klein et al: Annals of Internal Medicine 1997; 126 (3): 200-209
Expires November 2004

The study

Unblinded ?concealed randomised trial with intention-to-treat
Setting: ten acute hospitals, USA, Europe, Australia

126 patients (aged range 63 to 69 years; mean 67, 77% male) atrial fibrillation for >2 days undergoing DC cardioversion

Excluded if
  • received anticoagulant therapy for > 7 days
  • required urgent cardioversion due to haemodynamic instability
  • cardioembolic event within one month
  • contraindication to transoesophageal echocardiography or warfarin
  • childbearing potential and pregnancy could not be excluded
  • unable to be followed-up


Control Group: (n = 64, 56 analysed): received 3 weeks of warfarin before cardioversion, followed by 4 weeks of warfarin after.
Experimental Group: (n = 62, 62 analysed): anticoagulated and once INR 2.0-3.0, had a transoesophageal echocardiogram. If this showed no thrombus, patients were cardioverted immediately, and had 4 weeks of warfarin . If this showed thrombus in the left atrium, patients had warfarin for 4 weeks, followed by a repeat transoesophageal echocardiography. If the thrombus had resolved patients were cardioverted, otherwise cardioversion was withheld.

100% followed for 4 weeks

The evidence

Outcome Time to outcome CEREERRRR
(95% CI)		ARR
(95% CI)		NNT
(95% CI)
no cardioversion minutes 27
(42.2%)		 15
(24.2%)		 43%
(3% to 66%)		 18.0%
(1.87% to 34.1%)		 6
(3 to 54)
no sinus rhythm 4 weeks 27
(42.2%)		 28
(45.2%)		 -7%
(-59% to 28%)		 -2.97%
(-20.3% to 14.3%)		 -34
(NNT = 7 to infinity;
NNH = 5 to infinity)
embolic events 4 weeks 1
(1.56%)		 0
(0.00%)		 100%
(% to %)		 1.56%
(-1.48% to 4.60%)		 64
(NNT = 22 to infinity;
NNH = 68 to infinity)

Outcome Control Group
(SD)		 Experimental Group
(SD)		 Mean Difference
(95% CI)
time to cardioversion (weeks) 4.80
(0.97) 		0.60
(0.30) 		-4.2
(-3.9 to -4.5)

Comments

  1. Validity reduced as study was not blinded.
  2. Small study reduces the power to detect small differences.

Citation

  1. Klein AL, Grimm RA, Black IW, et al: Cardioversion guided by transesophageal echocardiography: The ACUTE pilot study. Annals of Internal Medicine 1997; 126 (3): 200-209
Contributor: Chris Ball and Clare Wotton, November 2000
Reviewer:

Clinical Question.
Patient atrial fibrillation
Intervention or Exposure transoesophageal ECG before DC conversion
Comparison DC conversion alone
Outcome sinus rhythm, embolic events