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Complications associated with Sapien 3, a next-generation balloon-expandable transcatheter heart valve, can be avoided with proper implantation and prosthesis sizing, a study found.

Implantation of a new permanent pacemaker was required in 16% of patients, while 31% either got a new pacemaker or had new conduction abnormalities. The latter conditions were tied to deeper device implantation (P=0.003) and oversized prostheses (P=0.007).

After multivariable adjustment, deep valve placement at the septal side was with new left bundle branch block (LBBB), right bundle branch block (RBBB), or implantation of a permanent pacemaker (OR 1.063, 95% CI 1.017-1.110). Other factors tied to these complications include prosthesis oversizing (OR 3.489, 95% CI 1.236-9.848) and longer QRS duration (OR 1.033, 95% CI 1.011-1.056).

"An adjustment of implantation height and careful adherence to the sizing algorithms may result in a reduction of new or worsened conduction abnormalities or permanent pacemaker implantation," according to , of German Heart Centre Munich, and colleagues.

"The important finding of this study lies in the higher-than-expected rates of new permanent pacemaker implantation and/or conduction abnormalities for the Sapien 3," , of McGill University Health Centre in Montreal, Canada, and colleagues wrote in an .

The data suggest that not all is well in the wake of the transcatheter aortic valve replacement (TAVR) revolution, as "the benefits of superior sealing afforded by the new Sapien 3 skirt appear to be counterbalanced by an increased incidence of conduction abnormalities," the editorialists continued.

Husser and colleagues noted that while there was no uptick in deaths, "permanent pacemaker implantation may limit clinical benefit from TAVR due to lack of AV-synchrony and right ventricular pacing," adding that it may also be "an important cause of prolonged hospital stay, thereby increasing procedural costs."

"Until now, newer generation TAVR devices appear to have positive effects on clinical outcomes," according to Piazza and colleagues. The present study highlights the possibility that "new device iterations, although designed with good intentions, can be associated with untoward and unexpected clinical outcomes."

A total of 244 TAVR recipients were analyzed in the investigation.

New permanent pacemakers were more likely to be required by those with previous RBBB (OR 11.965, 95% CI 3.406-42.026), atrial fibrillation (OR 3.996, 95% CI 1.567-10.192), previous unspecific intraventricular conduction abnormality (OR 10.022, 95% CI 1.644-61.083), and implantation depth at the nonseptal side (OR 1.066, 95% CI 1.066-1.127).

Prosthesis oversizing, however, was not an independent risk factor for pacemaker implantation.

Insertion of a new permanent pacemaker can be a preventative measure or a treatment for a preexisting indication for pacing, according to the authors. They acknowledged that it "may be a somewhat subjective endpoint to analyze, and the effect of implantation depth and oversizing may thus become more difficult to evaluate."

As for why LBBBs and RBBBs may arise from deep implantation, "a deeper positioning of the prosthesis below the aortic annulus might cause conduction abnormalities via mechanical stress and direct damage of the conduction system," they suggested.

And for that, the imaging equipment may be to blame.

"Using fluoroscopic images offers an approximation of implantation depth, which in certain cases may be subject to underestimation due to discrepancies between the annulus plane and prosthesis plane," the authors offered.

"The only accurate method to measure the true implant depth is when both the annulus and device are orthogonal to the viewing plane," Piazza and colleagues wrote. "Currently, however, physicians select a viewing angle perpendicular to either the aortic annulus or the delivery catheter, but not both."

"Given that our implant depths are on the order of millimeters, foreshortening of the anatomy or delivery catheter on 2D fluoroscopic imaging can skew the operator's understanding of the true implant depth. The effect of foreshortening invariably leads to implant depths deeper than intended without the operator noticing," they explained.

"A potential solution is to find the single fluoroscopic viewing angle (which exists) that provides both the annulus and delivery catheter in plane," a possibility that Piazza's group is currently investigating.