Newer FlexNav Delivery System Improves Placement of Portico TAVI Valve

BOSTON, MA—Rates of adverse outcomes at 30 days are low among patients with symptomatic severe aortic stenosis who undergo TAVI with the self-expanding Portico valve (Abbott), with the newer FlexNav delivery system allowing for an improved implant depth, according to findings from the CONFIDENCE registry.

Hemodynamic performance was excellent across valve sizes ranging from 23 to 29 mm, and perivalvular leak was mild or less in nearly all patients (98%) at 30 days, Helge Möllmann, MD (St. Johannes Hospital Dortmund, Germany), reported here at TCT 2022.

The overall rate of new permanent pacemaker implantation was relatively high at 19%, although Möllmann noted that when the optimal implant depth was achieved (2-4 mm), which was more likely with the newer delivery system, that figure came down to 12.6%.

Looking at results out to 1 year, there were low rates of all-cause and CV mortality regardless of which delivery system was used.

“The Portico self-expanding, intra-annular valve delivered excellent clinical results in a large real-world study in high and extreme surgical risk subjects,” Möllmann said at a press conference.

Robert Bonow, MD (Northwestern University Feinberg School of Medicine, Chicago, IL), commented to TCTMD that the Portico valve seems to have good hemodynamic performance and has some unique features, including a design with large, open cells that facilitate future coronary access.

He expressed concern, however, about the pacemaker rate, particularly as the use of TAVI increases in younger and lower-risk patients. “If the newer-generation [delivery system] allows you to position this precisely within that sweet spot of 2 to 4 mm, you’re going to reduce the pacemaker rate, but otherwise you’re talking about a 19% to 30% pacemaker rate, which would be a real concern in younger people,” he said. “The issue is going to be that when you put this into the hands of all the operators out there, how are they going to be able to position this so accurately?”

CONFIDENCE Registry

The Portico valve, a nitinol self-expanding stent that can be repositioned and retrieved until it is fully deployed, was approved by the US Food and Drug Administration last year, bringing a third option to American TAVI operators. It has large open cells that maintain coronary access and early valve functionality that ensures hemodynamic stability during deployment, Möllmann said. With four sizes ranging from 23 to 29 mm, it can be used to treat annulus sizes of 19 to 27 mm.

The first-generation delivery system came with either an 18- or 19-Fr sheath depending on valve size, whereas the second-generation FlexNav delivery system has an integrated sheath, bringing the insertion profile down to 14-15 Fr. The newer system also has a redesigned handle, a hydrophilic coating, and an added stability layer to prevent migration of the valve during deployment.

Across 28 centers in Australia and Europe, the prospective CONFIDENCE registry enrolled 1,001 patients treated with the Portico valve, with half involving the older delivery system (between October 2018 and January 2020) and half the FlexNav system (between March 2020 and July 2021).

Patient characteristics were similar in the two groups and were reflective of a typical high-risk TAVI cohort, Möllmann said. Mean age was about 82, and most patients (about 62%) were women. Mean STS score was roughly 4.5%. The only difference between the later and earlier cohorts was the minimum vessel diameter was smaller when the FlexNav delivery system was used (7.09 vs 7.42 mm; P = 0.0002), most likely due to the slimmer insertion profile, Möllmann said.

For the procedure, patients treated using the FlexNav system were more likely to receive conscious sedation (82.6% vs 69.9%) and less likely to require a procedure with an introducer sheath (24.0% vs 93.6%). Implant depth was lower with the newer system (4.5 vs 5.1 mm; P = 0.004). Procedural success was high in both groups (about 98% overall).

The primary endpoint encompassed VARC-2 event rates at 30 days. They were low overall, with no significant differences between older and newer delivery systems in terms of the following outcomes:

• All-cause mortality (3.2% vs 2.0%)
• CV mortality (3.0% vs 1.2%)
• Disabling stroke (1.6% vs 2.0%)
• Stage 3 acute kidney injury (1.4% vs 0.8%)
• Life-threatening bleeding (3.2% vs 3.6%)
• Major vascular complications (6.4% vs 8.2%)
• Overall permanent pacemaker implantation (17.4% vs 16.8%)
• New permanent pacemaker implantation (19.2% vs 18.9%)

The overall pacemaker rate varied by implant depth, rising from 12.6% at a depth of 2-4 mm, 17.4% at a depth of 4-7 mm to 21.8% at a depth of 7-10 mm, and 31.8% depths greater than 10 mm. The newer FlexNav delivery system makes it easier to achieve implant depths of 2-4 mm, Möllmann said.

He reported favorable data on hemodynamics and paravalvular leak at 30 days across valve sizes. In addition, there were low rates of mortality at 1 year, with numerically but not significantly lower rates among patients treated using the FlexNav delivery system—all-cause mortality (11.0% vs 13.7%) and CV mortality (7.3% vs 9.4%).

A Place for Portico?

An open question, Bonow said, is where the Portico valve fits into the landscape of TAVI in the US, which is dominated by valves from Medtronic and Edwards Lifesciences. Operators generally have a good feeling about which of those self-expanding or balloon-expandable devices, which have gone through multiple iterations, will work best for a given patient, he added.

Now, he said, “you have a new valve hitting the market. Are they going to feel comfortable in their next patient to suddenly choose this valve as opposed to the ones they have more experience with? Give it some time and see.”

Asked about choosing between the available TAVI valves, Möllmann said “the importance is to yield the best result for each individual patient.” Favorable characteristics of the Portico are the low gradients achieved in small annulus sizes and the design with large open cells, he said. “The large cells allow very easy access to the coronary arteries, so a patient with concomitant coronary artery disease may be treated better with this one in comparison to other devices which do not have these large cells where it might be more difficult to bring in the guiding catheter.”

Commenting at the press conference, panelist Deepak Bhatt, MD (Brigham and Women's Hospital, Boston, MA), with an eye on the economic perspective, said there is terrific potential for additional TAVI valves in the US. “I think as more valves enter clinical practice worldwide, it will hopefully lead to some downward pressure on pricing, which would be really a major advance,” he said.

That hasn’t happened yet in the US, but if it does, it would be good for both patients and the healthcare system, Bhatt noted. In the meantime, studies like this one help add to the TAVI knowledge base, he indicated, adding, “I think the more valves, really the better.”

Abbott has a next-generation TAVI valve—Navitor, which builds on the Portico—that received CE Mark approval in Europe in May 2021 for patients with high or intermediate surgical risk, but it is not yet available in the US. Data presented earlier this year indicate that it provides low adverse event rates and good hemodynamics at 1 year in patients with high-to-extreme surgical risk.