We appreciate the publication of the letter from Renilla et al concerning our article about the changes in cardiac conduction following implantation of a CoreValve prosthesis.1 After reading the letter carefully, we would like to make a few comments on their reflections.

It is true that this prosthesis has frequently been associated with the need for a pacemaker, especially when this percutaneous technique was starting to be introduced. One of the reasons is probably that pointed out by the authors: the lack of data on the time course of complete atrioventricular block secondary to valve implantation. During the early years of the technique, many of the indications for pacemaker insertion were due to the development of new conduction disturbances, other than complete atrioventricular block, with unknown natural courses. Although controversy remains to this day,2,3 in our experience, patients with new onset left bundle branch block after valve implantation are no more likely to need a pacemaker because of this acquired conduction disturbance than patients without this disorder. The course of patients who develop right bundle branch block after transcatheter aortic valve implantation appears to be different; in our series, this subgroup of patients seems to exhibit an early increase in the probability of needing a pacemaker.

As to setting an exact time limit to the causal relationship between implantation of the valved stent and the need for a permanent pacemaker, we agree with Renilla et al in that it is complicated. Although some authors establish a limit of 30 days, according to the latest European Society of Cardiology guidelines,4 if bradycardia is significant and does not resolve within an adequate period of observation after prosthesis implantation (established as 1 week), insertion of a permanent pacemaker is unavoidable. Regardless of this consideration, we cannot lose sight of the fact that these patients are very elderly and have a disease that affects the conduction tissue and impulse generation. Proof of this are the 2 patients (1.1%) who had recurrent syncopal episodes for whom we requested pacemaker implantation, although their atrioventricular conduction was intact, because late electrophysiological studies revealed sinus node dysfunction after 1 month and 20 months of follow-up, respectively.1