Original Title: Changes in the Pacemaker Rate After Transition from Edwards SAPIEN XT to SAPIEN 3 Transcatheter Aortic Valve Implantation. The Critical Role of Valve Implantation Height. Reference: Fernando De Torres-Alba et al. J Am CollCardiolIntv. 2016, online before print.

The aim of this study was to analyze pacemaker implantation rates with the new generation balloon expandable Edwards SAPIEN 3 valve and the possible factors associated to this event.

The introduction of the new generation Edwards SAPIEN lead to a reduction of paravalvular regurgitation, but there is concern that definite pacemaker rates may increase.

The first 206 patients receiving the new Edwards SAPIEN S3 were compared to 371 preceding patients receiving the previous generation valve SAPIEN XT.

Those that had previously received a pacemaker,or transapical, or valve in valve procedures, were excluded.

All conduction abnormalities, both new and old, were documented, as well as implantation height. All patients were monitored at least 7 days. There were no significant differences between baseline characteristics in the two populations.

Pacemaker implantation rate was significantly higher with the new generation valve (19.1% vs. 12.2%; p = 0.046). Implantation height was lower in those receiving pacemakers and this point resulted the only independent factor in multivariable analysis (OR 0.94 CI 95% 0.90 to 0.99; p = 0.009).

We can use the native annulus as reference to measure what percentage of the transcatheter valve stent is above the annulus in the aorta, and what percentage is in the ventricle, below the annulus.

An increased percentage in the ventricle was observed that could explain the higher pacemaker rate. This ratio went from 68%/32% (aorta/ventricle) in the first cases with SAPIEN S3to 75%/25% (aorta/ventricle)in the last cases, which is significant(p < 0.0001). This change in implantation height was associated with a difference in pacemaker rate (25.9% vs 12.3; p = 0.028).

Conclusion
Pacemaker implantation rate with the new generation balloon expandable SAPIEN S3 valve resulted higher compared to the previous generation SAPIEN XT. This increase could be avoided if the valve stent is >70% above the annulus.