Not All TAVR Valves the Same in Producing Embolic Debris

Liam Davenport

August 29, 2018

MUNICH — There are significant differences in the debris caught by embolic protection devices during transfemoral aortic valve replacement (TAVR) procedures, with the largest particles seen with balloon-expandable valves, say German researchers in findings they believe strengthens the case for universal embolic protection.

An analysis of 100 patients undergoing TAVR showed that the balloon-expandable Sapien 3 valve (Edwards) was associated with significantly more debris particles of at least 1 mm in diameter compared with the self-expandable CoreValve Evolut R (Medtronic) and the mechanically implantable Lotus valve (Boston Scientific).

The study, presented here at the European Society of Cardiology (ESC) Congress 2018, and published simultaneously in JACC: Cardiovascular Interventions, also showed that the embolic protection device captured fewer particles during procedures that used the Lotus valve than with the others, and that the total area of tissue was smaller with this valve.

Julia Seeger, MD, Department of Internal Medicine II, University of Ulm, Germany, who presented the study, told theheart.org | Medscape Cardiology that it's not clear why there were differences in the debris collected between the valves.

She pointed out that the relatively small number of patients included in the study means that it's difficult to draw firm conclusions.

However, Seeger said that the expandable valves cause more sheer stress when they are implanted, "so that could be one of the reasons, but I'm pretty sure you have to see more than 100 patients to really get that clear."

In terms of the use of embolic protection in TAVR procedures, she said that there are currently no selection criteria for determining which patients would benefit the most.

"There's nothing where you can say this patient is at a higher risk for stroke than another one is," she explained.

"Basically, we did a subgroup analysis and multivariate regression analysis and all that, but you don't see any independent predictors for saying this patient is at higher risk for stroke."

She consequently believes that if a clinician decides that they want to use the devices, "you do protection for all your patients."

Noting that her unit uses embolic protection in all of their TAVR patients, she said that "patients are coming to our institution and they're saying: I read you're doing this so I'm coming here exactly for that because I don't want to have a stroke."

A similar situation has developed in the United States, with patients wanting to have a device that could reduce their risk for stroke.

"At the moment in the US, they know that there are centers that are using it or not, and that's a decision point for the patient."

Seeger likened the case for embolic protection to that of other safety devices that initially were treated with skepticism but have become normalized over time.

"If you've got a seatbelt, you use it. Why wouldn't you use it? Would you say, I only use it if I'm driving really fast? It's basically the same here."

She said that the only factor holding back the wider adoption of embolic protection in Europe is money for reimbursement.

"There's still a lot of people in Europe who are very critical regarding protection, but I think in 2 or 3 years we'll be at the point [where it becomes accepted]."

"Even if you ask those who are very critical: If you were having TAVR, what would you want, they say, I would want to have the protection. That's the answer. So it's just the money in the end."

Stroke After TAVR

It has been reported that the rate of stroke after TAVR may be as high as 10%, with the greatest risk seen during the procedure itself. One MRI study even suggested that up to 98% of patients have some form of cerebral lesion after TAVR.

In 2017, the US Food and Drug Administration approved the Sentinel Cerebral Protection System (Claret Medical), which comprises proximal and distal filters to capture embolic debris dislodged during TAVR.

This was based on results from the SENTINEL randomized controlled trial, which showed a borderline significant reduction in stroke events following TAVR with the device (P = .05).

However, in 2017, Seeger and colleagues published a study in 802 TAVR patients showing that embolic protection with Sentinel was associated with a significant reduction in disabling and nondisabling stroke, from 4.6% to 1.4% vs no protection, at an odds ratio of 0.29 (95% confidence interval, 0.10 - 0.93; P = .03).

Hypothesizing that the risk for embolization with debris and subsequent stoke could differ between valves, the team then studied 100 consecutive patients who underwent TAVR with embolic protection.

Three types of valves were implanted: the balloon-expandable Sapien 3 valve (n = 42), the self-expandable CoreValve Evolut R (n = 35), and the mechanically implantable Lotus valve (n = 23).

The team collected the debris captured by the embolic protection device during the TAVR implantation and analyzed it using histopathology and histomorphometry, including particle size and total particle area.

The three patient groups were well balanced in terms of their baseline characteristics, although patients receiving the CoreValve Evolut 4 valve were significantly more likely to be female than those in the Lotus or Sapien 3 groups, at 68.6% vs 39.1% and 38.1%, respectively (P = .016).

The most common embolic material collected by the protection device was acute platelet-rich thrombus (99%), followed by arterial wall (84%), fibro-elastic tissue consistent with valve tissue (84%), calcifications (58%), foreign material (33%), myocardial fibers (14%), and necrotic core (12%).

There was no significant difference in the type of debris found in the protection device among the three valves.

However, procedures involving the Sapien 3 valve were significantly more likely than those using the other valves to result in particles of 1000 to 1999 µm in diameter in the proximal filter (P = .0103), and in particles 2000 µm or greater in diameter (P = .0122).

The researchers also found that the average number of particles collected in the proximal filter was significantly lower with the Lotus valve, at 89.8 ± 106.3, than for the CoreValve Evolut R or Sapien 3 valves, at 187.3 ± 176.8 and 172.3 ± 133.5, respectively (P = .035).

The Lotus valve was also associated with a significantly smaller total tissue area collected in the proximal valve compared with the CoreValve Evolut R and Sapien 3 valves, at 7.1 ± 6.3 mm2 vs 20.1 ± 19.0 mm2 and 21.3 ± 15.1 mm2, respectively (P = .0014).

The debris collected in the distal filter did not differ among the three valves.

Making the Case for Embolic Protection

In an editorial accompanying the publication, Didier Tchetche, MD, and Chiara de Biase, MD, Clinique Pasteur, Toulouse, France, say that the high proportion of debris found in the filters makes the case for using embolic protection in all TAVR procedures.

"Once we see what is captured...given the immediate and long-term consequences of disabling or cover stroke, it becomes intuitive that every single patient should have his brain protected," they write.

They add: "Even if we do not immediately see the consequences of cerebral emboli, it remains important to limit the occurrence of periprocedural events as much as we can."

As the wider adoption of embolic protection devices is hampered by the extra cost associated, Tchetche and de Biase say that "a first step could be to identify the patients at higher risk of stroke for a systematic use before a broader utilization."

Approached for comment, American Heart Association Past-President Mariell Jessup, MD, cardiologist and chief scientific officer at Leducq Foundation, Boston, Massachusetts, told theheart.org | Medscape Cardiology that the study was "very interesting."

She noted that, in the United States at least, the stroke risk associated with TAVR is "something that people fear but they don't talk about it too much."

"However, what I know is that the incidence of stroke is decreasing overall in TAVR, so it may be that the learning curve, the better valves, the different techniques have reduced the incidence of stroke," Jessup said.

"So the question is whether the community, particularly in the United States, feels that the risk–benefit and the additional cost will be justified in adding a filter to every case."

To that end, she said she has faith that the TAVR community will assess the need for embolic protection fully.

"The one thing I think we can say really clearly about the TAVR community is that they have gone step-by-step in trying to understand the implications of new valves vs the earlier valves, so I'm hoping they'll begin to address this issue of what benefit is there" with protection, she said.

"But it would need big trials to look at the impact on stroke and mortality from stroke because the incidence now has really decreased a lot," she added.

No funding or relevant financial relationships have been disclosed.

European Society of Cardiology (ESC) Congress 2018: Abstract 233. Presented August 25, 2018.

JACC Cardiovasc Intervent. Published online August 25, 2018. Abstract, Editorial

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