Solid 2-Year Outcomes for Portico, With Paravalvular Leak Rare

LONDON, England—Follow-up data from the PORTICO I study testing the self-expanding Portico transcatheter heart valve (Abbott) show a low rate of cardiovascular mortality and disabling stroke at 2 years, as well as continued low transvalvular gradients and large valve areas.

In this study of patients with severe symptomatic aortic stenosis deemed high risk for surgery, rates of all-cause mortality, cardiovascular mortality, and disabling stroke at 2 years were 19.7%, 9.6%, and 3.1%, respectively. The rate of new pacemaker implantation was 22.3%; although high, this was nearly identical to the rate observed at 1 year.

For lead investigator Lars Søndergaard, MD (Rigshospitalet, Copenhagen, Denmark), who presented the data during the late-breaking clinical trial session at PCR London Valves 2019, the results show that “the safety and efficacy outcomes of Portico remain consistent in this large, real-world study based on early experience.”

PORTICO I included 941 high-risk patients (mean STS score 5.8%), and 2-year follow-up was available for 627 patients. In terms of echocardiographic parameters, the mean aortic gradient declined from 49.7 mm Hg at baseline to 8.6 mm Hg at 30 days and remained low at 7.8 mm Hg at 2 years. The effective orifice area also remained effectively unchanged from 30 days to 2 years.

Not Sold on Paravalvular Leak

Perhaps the most interesting finding for physicians, though, was the low rate of paravalvular leak. Overall, moderate paravalvular leak was seen in 1.5% of patients at 2 years. Cardiovascular mortality did not significantly differ among patients without paravalvular leak and those with mild and moderate/severe leak, said Søndergaard.

Despite the follow-up data, some experts aren’t sold on the valve.

Hendrik Treede, MD, PhD (University Hospital Bonn, Germany), who chaired the session, said that while the valve has advantages over other devices with respect to coronary access, it may also have disadvantages. In fact, he questioned the rate of paravalvular leak observed in PORTICO I, noting that much higher rates have been seen in other studies, including the PORTICO Investigational Device Exemption (IDE) trial presented at TCT 2019. In that study, which included patients at high or extreme risk for surgery, moderate or severe paravalvular leak at 1 year was observed in 7.8% of those treated with Portico versus 1.5% for those treated with other commercially available valves.  

“The results are a bit contradictory,” Treede told TCTMD. “They seem almost a little too good in my mind based on real-life experience.”

Also speaking with TCTMD, João Cavalcante, MD (Minneapolis Heart Institute, MN), said even mild paravalvular leak with any device might be a bigger issue as TAVR moves into lower-risk patients. “If we implant a valve in somebody that is 80 years old and they have a life expectancy of another 2, 3, or 5 years, that might not be significant,” said Cavalcante. “Mild paravalvular leak over 10 or 15 years is certainly different.”

Right now, the rate of mild-to-moderate paravalvular leak with Portico is “probably not within the ballpark” of other TAVR platforms, he said. As the valve evolves, though, with the addition of a sealing skirt, for example, it may lower the rate of leak. “A new iteration might be able to tackle that, but next comes the pacemaker issue,” said Cavalcante. The addition of a sealing skirt can put more pressure on valve structures leading to conduction disturbances requiring a pacemaker, he said.

Panelist Alexandra Lansky, MD (Yale University School of Medicine, New Haven, CT), also questioned the seemingly low rates of paravalvular leak in PORTICO I compared with the IDE trial, as well as the high rate of pacemaker implantation.

Søndergaard said there’s a learning curve with this transcatheter valve, and that as operators gain experience with its use those rates will come down. In fact, an analysis of the PORTICO IDE trial showed better safety and efficacy in the second half of the trial over the first, he noted. Additionally, a second study presented at PCR London Valves showed the rate of new pacemaker implantation was 14.6% in 100 patients treated with Portico using their next-generation FlexNav delivery system, down from 27.7% with the older delivery system, suggesting experience can mitigate this risk. However, the rate of moderate-or-greater paravalvular leak at 30 days remained at 6.5% in the FlexNav cohort.   

Concerns About Leaflet Thrombosis

While Portico attempts to gain a foothold in a growing TAVR marketplace, the device has had its share of difficulties. In 2015, Raj Makkar, MD (Cedars-Sinai Medical Center, Los Angeles, CA), and colleagues published early data from the PORTICO IDE study showing reduced leaflet motion on CT screening in 16 of 37 patients treated with the Portico valve. That led to a pause in enrollment and several changes in valve design.

During the session, Treede homed in on those concerns, asking Søndergaard if they observed any problems with respect to impaired leaflet motion.  

“We’re talking about subclinical leaflet thrombosis,” said Søndergaard. “It’s not clinical valve thrombosis where the patient has a high gradient and symptoms and you need to do something. It’s subclinical thrombosis, which is something you can see on the CT scan and also on transesophageal echo where one or two of the leaflets are thickened and often not moving. The interesting thing about it is the gradient is almost normal, at least in the normal range. It’s not something you’re going to pick up on a transthoracic echo in your clinic and the patient will have no symptoms.”

While hypoattenuated leaflet thickening and impaired mobility may be more likely to occur with Portico given its intra-annular positioning, the problem has also been documented with the other transcatheter and surgical heart valves, he said. Whether it will have an impact on patient symptoms or translate into adverse clinical outcomes, such as stroke or TIA, or even affect valve durability, is not fully known, “but I would say today there is no evidence it’s going to affect clinical outcomes,” said Søndergaard. “It’s not going to affect my choice of valve.”

At 2 years in PORTICO I, freedom from structural valve deterioration was 99.1%.

Treede said he’s still not convinced and doesn’t expect these latest results will impact his practice. “Even if thrombus is subclinical, I still see it as a problem,” he told TCTMD. If he needed a self-expanding valve with a higher stent frame, his preference is the Evolut platform (Medtronic). “I would take advantage of the supra-annular position, stronger radial force, and lower leaks,” he said. “Of course, accessibility of the coronary arteries is a problem, but this doesn’t account for the disadvantages.”

Finally, Cavalcante said, the field might also need a better refinement of “mild” leaks. “Is mild really mild and can we have a better technology within the cath lab to adjudicate it?” he asked. “That’s the time when we’d be able to fix and do something about it. We have been looking into this with MRI, which is a way to provide better discrimination, but that’s after the fact.”