麻豆传媒

The number and volume of new cerebral ischemic lesions after transcatheter aortic valve replacement (TAVR) were particularly high in people with bicuspid aortic valves (BAVs), according to one center in China.

Results of diffusion-weighted magnetic resonance imaging (MRI) several days after TAVR were compared between these patients and their peers with tricuspid valves. The bicuspid group had:

• More new lesions: median 4.0 vs 2.0 (P=0.008)

• Higher total lesion volumes: 290 vs 140 mm³ (P=0.008)

• Larger lesions: 70.0 vs 57.5 mm³ per lesion (P=0.037)

• Greater likelihood of lesions larger than 1 cm³: 28.6% vs 10.9% (P=0.005)

"Further studies are necessary to show whether TAVR is suitable for BAV patients when considering brain injury complications. Cerebral embolic protection devices may be recommended for TAVR, especially in BAV patients, to avoid cerebral ischemic lesions that potentially deteriorate neurological and cognitive function," suggested Jian'an Wang, MD, PhD, of Second Affiliated Hospital, Zhejiang University School of Medicine in China, and colleagues.

"Though some studies showed that new ischemic lesions are not linked to apparent neurological symptoms, there is evidence that perioperative ischemia may increase the risk of cognitive function and long-term dementia," the researchers wrote in their study online in the .

Bicuspid and tricuspid patients shared similar overt stroke rates (2.4% vs 1.7%) after TAVR.

The availability of diffusion-weighted MRI today means that new silent lesions can be detected in most if not all patients undergoing TAVR, noted Marc Radermecker, MD, PhD, of Sart-Tilman University Hospital Center in Liège, Belgium, and colleagues, writing in an . "The tissue-based paradigm for CNS [central nervous system] injury assessment therefore raises major concerns with regard to the significance of these so called 'silent' or 'covert' brain injuries."

Nevertheless, the editorialists agreed that embolic protection should be used in TAVR for people with bicuspid valves, adding that device improvements and procedure refinements are needed as well.

For the study, Wang and co-authors identified 258 consecutive severe aortic stenosis patients who underwent transfemoral TAVR in 2016-2019. A total of 204 were included in the analysis after the researchers excluded people unable to tolerate MRI and based on other criteria.

Patients with bicuspid valves constituted 40.7% of the TAVR cohort. Compared with the tricuspid group, these patients were significantly younger (median age 76 vs 79, P=0.004) and lower-risk (Society of Thoracic Surgeons score of 4.87 vs 6.38, P=0.044).

TAVR on bicuspid anatomy was associated with more pre-dilatation and trended toward longer procedures without reaching statistical significance, compared with tricuspid TAVR, the researchers reported.

Bicuspid morphology was type 0 in two out of three cases. Wang and co-authors pointed out that European and Western countries tend to have a higher prevalence of type 1 morphology, according to the literature.

Diffusion-weighted MRI was performed at baseline and again an average of 5.7 days after TAVR.

Study limitations, the investigators said, included that longer follow-up is required for mortality, stroke, neurological, and cognitive outcomes, and that the study involved just one center and thus has the potential for bias stemming from excluding patients who were possibly clinically worse off and not able to tolerate MRI.

In any case, it is questionable whether TAVR is the right choice for patients with bicuspid valve morphology in the first place, Radermecker and co-authors said.

"They are much younger than their TAV [tricuspid aortic valve] counterparts and are predominantly at lower risk according to current scoring systems. As such, both their lifestyle and life expectancy expose them to every unresolved issue of TAVR, namely suboptimal valve deployment and possibly accelerated valve failure, a need for pacemakers, and worrying neurological risk," the editorialists wrote.

They argued that modern surgical aortic valve replacement may be the better choice for these patients, given the prospect of a properly fixed prosthesis and correction of various anomalies associated with bicuspid morphology (e.g., ascending aorta anomalies, impeachment of the anterior mitral leaflet, and left ventricular outflow tract anomalies).

Bicuspid aortic valve patients had been excluded from the major TAVR trials due to their unique morphological features.

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