乌鸦传媒

Use of a patient-specific approach to optimize self-expanding transcatheter aortic valve replacement (TAVR) positioning reduced the need for permanent pacemaker (PPM) implants down the road, a prospective single-institution study showed.

When the anatomically based "MIDAS" technique was applied to a consecutive series of patients undergoing minimalist TAVR with Evolut devices, the PPM rate dropped from 9.7% to 3.0% (P=0.035), according to a team led by Hasan Jilaihawi, MD, of NYU Langone Health in New York City.

Similarly, the rate of new left bundle branch block (LBBB) went down from 25.8% to 9.0% (P<0.001), the group reported online in .

Under MIDAS (Minimizing Depth According to the Membranous Septum), operators aim for a pre-release depth in relation to the non-coronary cusp that is no longer than the length of the patient's membranous septum -- but also no higher than 1 mm to minimize risk of device embolization.

"We have now developed a technique that is not only reproducible but is also easily learned and simply interpreted," the authors explained, adding that their reported rates of PPM implantation and LBBB are "significantly lower than previously reported with ."

Just recently, the PARTNER 3 and CoreValve Low Risk trials in patients at low surgical risk showed PPM implant rates of 17.4% with the Evolut line, 6.6% with the balloon-expandable Sapien 3, and 4.1%-6.1% with surgery.

The current work represents "a major step forward in the field," and the results "challenge the valve class effect concept regarding conduction disturbances post-TAVR," said Josep Rodés-Cabau, MD, of Quebec Heart and Lung Institute at Laval University in Quebec City, Canada, in an accompanying editorial.

"While the generalization of the safety and efficacy of this technique remains to be determined, obtaining single-digit rates for PPM implantation and new-onset LBBB post-TAVR (similar to or lower than those of surgical aortic valve replacement) is of high clinical relevance in the era when TAVR is going to expand to the treatment of low risk and younger patients," Rodés-Cabau wrote.

The MIDAS creators cautioned that it may be a challenge to avoid PPM implants in the high-risk group of patients with a membranous septum shorter than 2 mm, as even an "overly aggressive anatomically based high implant approach may not be easily achievable without increasing the risk of device pop-out."

Furthermore, there may be possible imaging limitations as a shorter membranous septum may approach the minimum resolution of CT, they said.

To capture factors that contributed to need for PPM implantation, Jilaihawi and colleagues performed a detailed retrospective analysis on 248 consecutive Evolut recipients at Langone treated with the standard TAVR approach -- aiming for 3-4 mm implant depth (in relation to the non-coronary cusp) and recapturing and repositioning when the device landed considerably lower. Patients with prior PPM implantation were excluded. Devices used were Medtronic's Evolut R, Evolut Pro, and Evolut 34XL.

This analysis revealed that use of the large Evolut 34XL (OR 4.96, 95% CI 1.68-14.63) and implant depth exceeding membranous septum length (OR 8.04, 95% CI 2.58-25.04) were independent predictors of later PPM implantation.

From there, operators came up with the MIDAS technique and applied it prospectively to another 100 consecutive patients.

Besides bringing down the PPM implant rate to 3.0%, there were no more cases of valve embolization, dislocation, or need for a second valve.

The standard and MIDAS groups shared similar membranous septum lengths but diverged in average actual device depth, such that the standard group tended to have Evolut devices positioned deeper (3.3 mm vs 2.3 mm, P<0.001).

"The His bundle passes through the membranous septum, a few millimeters beneath the non-coronary/right coronary cusps. It is therefore not surprising that a deeper valve implantation increases the likelihood of mechanical damage of the His bundle leading to a transient or persistent conduction disturbance," according to Rodés-Cabau.

Rodés-Cabau noted various limitations of the current study, including its single-center nature, limited sample size, need for longer-term follow-up, and the potential for selection bias. Rodés-Cabau also pointed to a lack of certain specific details such as management of conduction disturbances and number of valve recapture and/or repositioning attempts.

MIDAS will be further tested in an upcoming collaboration among centers in the U.S., Europe, and China. Also in the works is a prospective multicenter study designed to standardize practices using the Evolut Pro, Jilaihawi's team said.

It is to be seen whether the MIDAS approach can help the experience of Lotus Edge, another repositionable TAVR belonging to a line that has been troubled by PPM issues.