Response to letter regarding article, 'Clinical impact of persistent left bundle-branch block after transcatheter aortic valve implantation with CoreValve revalving system'

We appreciate the interest of Prinzen et al about our article,1 but some of their comments need to be addressed. Prinzen et al analyzed a mixed population of patients treated with CoreValve or Edwards Sapien prostheses.2 Of note, their different influence on the cardiac conduction system is well known,3 with the CoreValve being more prone to determine conduction disturbances as a consequence of the larger frame. Accordingly, we decided to specifically focus on the CoreValve, pooling >800 patients, which is more than double the population considered by Prinzen et al. It is clear that the internal and external validity (ie, the extent of systematic biases and the generalizability of the results) are highly affected by the sample size. Prinzen et al excluded patients who underwent pacemaker implantation within 30 days after transcatheter aortic valve replacement, which, in our opinion, makes little …