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AV node ablation and implantation of mode switching dual chamber pacemakers: effective treatment for drug refractory PAF
  1. T LEVY,
  2. S WALKER,
  3. V PAUL
  1. Royal Brompton and Harefield NHS Trust
  2. Hill End Road
  3. Harefield, Middlesex UB9 6JH, UK

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    Editor,—Marshall et alstate that the combined procedure of atrioventricular (AV) node ablation and permanent pacemaker insertion for medically refractory paroxysmal atrial fibrillation (PAF) is justified on the basis of their study results.1 We agree that in many patients with this condition AV node ablation and pacemaker insertion can improve the perceived quality of life; however, we feel that it is in the patient’s best interest that this procedure be performed in a staged manner with at least one month between pacemaker insertion and ablation.

    Lau et al previously identified a group of patients with drug resistant PAF in whom DDDR pacing prevented the need for subsequent AV node ablation.2 Their conclusion was that up to a third of patients with drug refractory PAF may derive benefit from sensor driven atrial pacing alone and that this treatment can result in an improvement in patient perceived quality of life, without additional AV node ablation.

    Permanent blockade of the AV node results in lifelong ventricular pacemaker dependency. This can result in long term deterioration in left ventricular function,3 the development of mitral regurgitation,4 and symptoms of dyspnoea, tiredness, and exercise intolerance. Therefore, to proceed directly to a combined AV node ablation and pacemaker insertion procedure is to deny a significant subgroup of patients the potential benefits of not having ablation. We suggest that a trial period of rate responsive atrial pacing be undertaken in patients with drug refractory PAF before ablation. This will enable those patients who will benefit from pacing alone to be identified, and thus prevent them undergoing unnecessary AV node ablation.

    We appreciate that there are potential cost implications to this staged approach; however, any increase in costs incurred may be offset by the decreased number of patients eventually requiring AV node ablation, and by the decrease in long term complications of ventricular pacing dependency.

    References

    This letter was shown to the authors, who reply as follows:

    Levy et al raise an important question. The timing of AV node ablation in relation to pacing is currently the subject of some debate, although most published series describe ablation and pacing as a single procedure. However, the consensus of a recent discussion group report1-1 was that ablation and pacing for PAF could be offered as a staged procedure to allow patients to pass the early high risk period for pacemaker lead displacement before rendering them pacemaker dependent.

    There is also increasing interest in pacing alone as a mode of treatment for drug resistant PAF and this raises the suggestion that dual chamber pacing should be carried out as a standalone procedure with later ablation only if there is no improvement in symptoms. In contrast to pacing for sinus node disease (our study specifically excluded patients with significant bradycardia) the data to support pacing alone for PAF are far from clear. Levy et al refer to early data from the PA3 study in which some patients’ symptoms improved with DDIR pacing alone.1-2However, data from the same study also suggested that in general DDIR pacing does not prevent atrial fibrillation and indeed shortens the time to recurrence compared to no pacing (pacemaker programmed to DDI at 30 beats/min).1-3 Other studies of pacing alone for PAF have been disappointing. While some have shown minor reductions in atrial fibrillation frequency,1-4 none has demonstrated quality of life benefits. We accept that alternative atrial pacing sites and novel pacing algorithms may allow pacing to improve quality of life without the need for AV node ablation.

    With regard to the complications of AV node ablation cited, the mitral regurgitation reported in two patients by le Tourneauet al was moderate before ablation and became severe soon after.1-5 Improved ventricular filling (achieved by good rate control) may well worsen mitral regurgitation and we advocate that patients with moderate mitral regurgitation undergo valve surgery before ablation and pacing; in patients with PAF this may well reduce left atrial pressure sufficiently to reduce the frequency of atrial fibrillation episodes. Possible deterioration of left ventricular function associated with long term right ventricular apical pacing has to be weighed against the possibility of patients developing tachycardia induced left ventricular dysfunction if they continue to be exposed to frequent prolonged episodes of rapid atrial fibrillation; indeed, several studies have shown improvement in left ventricular systolic function after ablation and pacing for PAF.1-6 In addition, alternative sites for right ventricular pacing (or even biventricular pacing) may reduce the potential for long term left ventricular dysfunction.

    In summary, we feel that either a one or two stage procedure is acceptable. A pragmatic approach might be to offer patients the choice of ablation and pacing at one sitting, which will improve symptoms but require pacemaker dependence, or a two stage procedure, which may avoid the need for ablation but may require a second admission for symptomatic improvement. Given the high symptom burden of PAF patients being considered for ablation and pacing, we suspect many will choose the first option.

    References

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