Study Pinpoints Predictors of New Conduction Abnormalities, Pacemaker With Sapien 3

In patients undergoing TAVR with Sapien 3, implantation depth and prosthesis oversizing are strongly correlated with the occurrence of new conduction abnormalities and/or permanent pacemaker implantation, a single-center study has found. The results, published in February issue of JACC: Cardiovascular Interventions, suggest that operators could adjust their technique as a means to avoid these complications. 

Notably, nearly 1 in 3 patients without preexisting conduction abnormalities developed them or required a pacemaker in the current study. Previous reports have suggested that the incidence of these complications after balloon-expandable TAVR ranges from 8% to 30%, putting the 31% found here slightly out of range.

Oliver Husser, MD, of Deutsches Herzzentrum München (Munich, Germany) and colleagues examined potential determinants of new pacemaker and conduction abnormalities with the balloon-expandable SAPIEN 3 valve (Edwards Lifesciences) in 244 consecutive patients (mean age 81 years; mean logistic EuroSCORE 16%) treated at their institution—208 of whom had no previous pacemaker and 184 of whom had neither pacemaker nor conduction abnormalities at baseline. The majority of cases (82%) utilized the 23- or 26-mm valve, with 18% utilizing the 29-mm valve.

The device success rate was 98%. Mean implantation depth was 26% (range, 6% to 48%), and the median percentage of oversizing by annular area and perimeter was 7% and 2%, respectively. In more than 75% of cases, prosthesis selection was within range, while it was undersized in 12% and oversized in 11%.

Permanent pacemakers were implanted prior to discharge in 16% of patients without a previous pacemaker. Compared with patients not needing a new pacemaker, those who did were more likely to have A-fib, complete right bundle branch block (RBBB), or bradycardia at baseline. Additionally, patients needing a pacemaker showed a trend (P = .14) toward having had deeper implantation compared with nonpacemaker patients.

Multivariable analysis showed several factors including previous RBBB, A-fib, lower heart rate on admission, and previous unspecific intraventricular conduction abnormality to be independent predictors of need for permanent pacemaker among patients who did not have one previously.

Approximately 1 in 3 patients (31%) developed either new or worsened conduction abnormalities or were implanted with a pacemaker. In these patients, implantation depth was lower, especially at the septal side (29 ± 8% vs 25 ± 7%; P = .003) and the rate of oversizing was greater (19% vs 6%; P = .007).

Independent predictors that emerged for new or worsened conduction abnormalities or pacemaker were: implantation depth at the septal side, out-of-range oversizing, and QRS duration on admission.

“In a comprehensive analysis, we identified a strong influence of implantation depth and extreme prosthesis oversizing on the occurrence of new or worsened [conduction abnormalities],” Husser and colleagues write. They note that “deeper positioning of the prosthesis below the aortic annulus might cause [conduction abnormalities] via mechanical stress and direct damage of the conduction system.”

While some studies have shown that new-onset conduction abnormalities after TAVR with balloon-expandable valves may be dynamic—and that a certain percentage resolve—the degree of resolution during follow-up is unclear, Husser and colleagues observe. They conclude that future studies should examine whether higher implantation and avoidance of extreme oversizing lead to a decrease in new permanent pacemaker and new or worsened conduction abnormalities with Sapien 3.

Call for Closer Scrutiny of New Iterations

In an editorial accompanying the study, Nicolo Piazza, MD, PhD, of McGill University Health Center (Montreal, Canada), and colleagues say the predictors of new pacemaker and/or conduction abnomalities seen in the study are not surprising and have been previously reported with other balloon-expandable devices including Sapien XT. But they express concern over the higher-than-expected rates of these events with the Sapien 3.

Therefore, the findings “highlight that new device iterations, although designed with good intentions, can be associated with untoward and unexpected clinical outcomes [and] reinforce the argument that new TAVR devices need to be prospectively studied using systematic and robust clinical protocols,” Piazza and colleagues argue.

The editorialists also point out data missing from the study that might be useful in interpreting its results. Specifically, the depth of implant according to device size is important, they say, in order to understand the impact on clinical practice, since frame height differs across device sizes. Reporting the implant depth in millimeters, rather than as a percentage, might help in determining a maximum cut-off depth to mitigate the risk of pacemaker and conduction disorders.

“As we move toward younger and lower surgical risk patients, the incidence, mechanisms, implications, and potential solutions to lessen the risks of conduction abnormalities and need for [permanent pacemaker implantation] following TAVR need to be further elucidated,” Piazza et al conclude.

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Sources: 
1. Husser O. Pellegrini C, Kessler T, et al. Predictors of permanent pacemaker implantations and new-onset conduction abnormalities with the SAPIEN 3 balloon-expandable transcatheter heart valve. J Am Coll Cardiol Intv. 2016;9:244-254.
2. Piazza N, Lauzier P, Mylotte D. Transcatheter aortic valve replacement and new conduction abnormalities/permanent pacemaker: can we achieve the intended implant depth [editorial]? J Am Coll Cardiol Intv. 2016;9:255-258. 

Disclosures:

• Husser reports receiving minor travel grants from Edwards Lifesciences. 
• Piazza reports serving as a consultant and proctor for and on the SURTAVI steering committee; serving on the scientific advisory board of Medtronic; serving as a consultant and proctor for MicroPort; serving as a consultant for and equity shareholder in HighLife; and being a cofounder of FluoroCT. 

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