Bradycardia: ventricular pacing increased thromboembolism

Clinical bottom line (level 1b)

  1. Patients given ventricular pacing were more likely to suffer a thromboembolism than those given atrial pacing.
  2. Patients with symptomatic bradycardia who were given ventricular pacing, had no clear difference in mortality or atrial fibrillation than those given atrial pacing.

Andersen et al: Lancet 1994; 344: 1523-1528

Expires August 2003

The study

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

225 patients (aged mean 75 years, 63% female) symptomatic bradycardia < 50 beats per minute or symptomatic PRS pauses >2 seconds

Excluded if
  • grade 1,2,3 atrio-ventricular block
  • chronic atrial fibrillation
  • bifascular bundle branch block
  • blood pressure >250/120 mmHg
  • atrial fibrillation >50% of time (2-4 days before implantation)
  • <50 years old
  • atrial fibrillation with RR interval >3 seconds
  • cardiac surgery planned
  • cancer
  • cerebral disease
  • atrial fibrillation with QRS rate <40 beats per minute
  • stroke within the previous 3 months
  • follow-up not possible
  • major surgery, non cardiac
  • Wenckebach block <100 beats per minute
  • refusal


    • Control Group: (n = 110, 110 analysed): atrial pacing
    Experimental Group: (n = 115, 115 analysed): ventricular pacing
    Patients had an atrial pacing test during implantation at 100 beats per minute; 1/1 atrio-ventricular conduction was required for an atrial pacemaker to be implanted. If second degree block occurred at a pacing rate <100 beats per minute, the lead was implanted in right ventricle. Patients in ventricular group always had a ventricular lead implanted whatever the result of the atrial pacing test.
    100% followed for ?
    Outcome notes:
    • atrial fibrillation : diagnosed by ECG, at one or more follow-up visits
    • thromboembolism : stroke was diagnosed when neurological symptoms presumably cerebral ischaemic origin persisted for >24 hours or if patient died within 24 hours from an acute cerebrovascular event. Peripheral embolus was diagnosed if verified at embolectomy or necropsy. Only the first thromboembolic event was classified as an endpoint.

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNH
    (95% CI)
    death unknown 21
    (19.1%)    		 25
    (21.7%)    		 -14.0%
    (-91.0% to 32.0%)    		 -2.65%
    (-13.2% to 7.88%)    		 38
    (NNT = 13 to infinity;
    NNH = 8.00 to infinity)
    atrial fibrillation unknown 15
    (13.6%)    		 26
    (22.6%)    		 -66.0%
    (-196% to 7.00%)    		 -8.97%
    (-19.0% to 1.01%)    		 11
    (NNT = 99 to infinity;
    NNH = 5 to infinity)
    thromboembolism unknown 6
    (5.45%)    		 20
    (17.4%)    		 -219%
    (-664% to -33.0%)    		 -11.9%
    (-20.1% to -3.81%)    		 8
    (5 to 26)

    Comments

    1. The study was too small to show any clear difference in mortality or atrial fibrillation between the two treatments.
    2. Six patients in the ventricular pacing group died from stroke, compared with one in the atrial pacing group.
    3. There was no difference in New York Heart Association classification of heart failure at follow-up between the two groups.

    Citation

    1. Andersen HR, Thuesen L, Bagger JP, et al: Prospective randomised trial of atrial versus ventricular pacing in sick-sinus syndrome. Lancet 1994; 344: 1523-1528
    Contributor: Clare Wotton and Musab Hayatli, August 1999
    Reviewer:

    Clinical Question.
    Patient symptomatic bradycardia
    Intervention or Exposure ventricular pacing
    Comparison atrial pacing
    Outcome mortality