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Maurizio Gasparini, Long-term survival in patients undergoing cardiac resynchronization therapy: the importance of atrio-ventricular junction ablation in patients with permanent atrial fibrillation: reply, European Heart Journal, Volume 29, Issue 17, September 2008, Pages 2182–2183, https://doi.org/10.1093/eurheartj/ehn291
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As Drs Foley and Leyva pointed out in their letter, device features such as ventricular rate regularization and ventricular trigger mode may be important to regularize heart rate trying to maximize biventricular capture in atrial fibrillation (AF) patients treated with cardiac resynchronization therapy (CRT). In our patient series1 of permanent AF patients with preserved atrio-ventricular junction (AVJ), ventricular trigger mode as well as ventricular rate regularization/stabilization features, such as Conducted AF Response™ or Ventricular Rate Regularization™, were activated once available. For Guidant devices, these features were incorporated in the devices from 2001 onwards, whereas for Medtronic models these were included only from 2003. It seems rather surprising, as mentioned in the letter by Foley and Levya, that in the Khadjooi study (covering up to 6.8 years of follow-up), ventricular trigger mode could have been activated in all AF patients, even those implanted before 2001.
These perplexities are further confirmed through the comparison between the survival curve of our study,1 in which the device features were activated once available, and the Khadjooi study,2 in which these features were reported to have been activated in all AF patients. In fact, survival from death from any cause was found to be very similar between the two AF groups with preserved AV conduction (Figure 1, survival curve C, dashed red for Gasparini et al. vs. B, solid blue for Khadjooi). These two clinically similar groups, although coming from different clinical realities, presented identical long-term outcome. In this context, either there were little or no differences in the rate regularization features activated between these groups, or any differences did not translate into important effects on outcome. When the Kaplan–Meier survival curve of permanent AF patients treated with AVJ ablation (Figure 1, curve D, dotted green for Gasparini et al.) derived from our experience is compared with the two other curves of patients with preserved AVJ conduction (Figure 1, curve C, dashed red for Gasparini et al., and B, solid blue for Khadjooi et al.), the significant protective effects of AVJ ablation on all-cause mortality become striking. Even though yearly mortality rate for the AF population is not explicitly specified in the Khadjooi study (Figure 1, curve B, solid blue), the survival pattern of this group is superposed to that of our experience (Figure 1, curve C, dotted red) and therefore yearly mortality may be estimated to be around 14 per 100 patients-year compared with a significantly lower incidence (4.6 per 100 patients-year) of events in the ablated AF group (Figure 1, curve D, dotted green).
