Sick sinus syndrome: atrial pacing reduced death and thromboembolic events better than ventricular pacing.

Clinical bottom line (level 1b)

  1. Patients with sick sinus syndrome who received single-chamber atrial pacemakers compared with single-chamber ventricular pacemakers were less likely to die (NNT = 7 at 5.5 years) or have thromboembolic events (NNT = 9 at 5.5 years) .
  2. There was no clear effect on the occurrence of atrial fibrillation.
Andersen et al: Lancet 1997; 350: 1210-1216
Expires October 2003

The study

Unblinded ?concealed randomised trial with intention-to-treat
Setting: university hospital, Denmark

225 patients (aged mean 76, 63% female) with sick sinus syndrome requiring their first pacemaker

Excluded if
  • atrioventricular conduction < 100 beats/min during atrial-pacing test


    • Control Group: (n = 115, 115 analysed): single-chamber ventricular pacing
    Experimental Group: (n = 110, 110 analysed): single-chamber atrial pacing

    100% followed for 5.5 years
    Outcome notes:
    • atrial fibrillation : found on ECG during follow-up visit
    • thromboembolic event : stroke or arterial embolism

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    death 5.5 years 57
    (49.6%)    		 39
    (35.5%)    		 28%
    (2% to 48%)    		 14.1%
    (1.33% to 26.9%)    		 7
    (4 to 75)
    atrial fibrillation 5.5 years 40
    (34.8%)    		 26
    (23.6%)    		 32%
    (-3% to 55%)    		 11.2%
    (-0.64% to 22.9%)    		 9
    (NNT = 4 to infinity;
    NNH = 160 to infinity)
    thromboembolic event 5.5 years 26
    (22.6%)    		 13
    (11.8%)    		 48%
    (4% to 72%)    		 10.8%
    (1.05% to 20.5%)    		 9
    (5 to 95)

    Comments

    1. Patients were randomised in blocks of ten.
    2. Four patients in the atrial pacing group developed atrioventricular block.
    3. The study is too small to show any difference between the two groups for the occurrence of atrial fibrillation.

    Citation

    1. Andersen HR, Nielsen JC, Thomsen PE, et al: Long-term follow-up of patients from a randomised trial of atrial versus ventricular pacing for sick-sinus syndrome. Lancet 1997; 350: 1210-1216
    Contributor: Chris Ball and Clare Wotton, October 1999
    Reviewer:

    Clinical Question.
    Patient sick sinus syndrome
    Intervention or Exposure atrial pacemaker
    Comparison ventricular pacemaker
    Outcome death, thromboembolic event