Cerebral Embolization During TAVR Comparable Across Access Routes, Devices

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Cerebral microembolization is inherent to transcatheter aortic valve replacement (TAVR) but is not associated with increased neurological deficits or acutely impaired neurocognitive function, according to a study published online August 16, 2012, ahead of print in Circulation. In addition, no difference was seen in the number of new brain lesions between the transfemoral or transapical approaches.

Philipp Kahlert, MD, of the University of Duisburg-Essen (Essen, Germany), and colleagues retrospectively analyzed 83 high-risk patients with severe aortic stenosis who underwent either transfemoral (n = 26) or transapical (n = 25) TAVR with the Sapien device (Edwards Lifesciences, Irvine, CA) or transfemoral TAVR with the CoreValve prosthesis (n = 32; Medtronic, Minneapolis, MN). Transcranial Doppler imaging was used to detect high-intensity transient signals (HITS) at baseline, during TAVR, and at 3 months.

No Difference in Lesion Incidence

Procedural success was 100% and overall mortality was 8.4% at 30 days and 12.0% at 3 months, with no differences among the 3 treatment groups.

Procedural HITS were identified in all patients, predominantly during manipulation of the calcified aortic valve while positioning and implanting the devices. The Sapien valve tended to cause more HITS during positioning, while CoreValve tended to cause more HITS during implantation (table 1).

Table 1. Procedural High-Intensity Transient Signals (HITS)

 

Transfemoral CoreValve
(n = 32)

Transfemoral Sapien
(n = 26)

P Value

Propagation and Placement of the Valvuloplasty Balloon

20.0

19.5

0.010

Valve Positioning

78.5

259.9

< 0.001

Valve Implantation

397.1

88.2

< 0.001


There were no overall differences between transfemoral and transapical TAVR or between the Sapien and CoreValve devices.

Two patients receiving transfemoral TAVR with a Sapien valve experienced procedural stroke, which was fatal in 1 case. In the other patients, there were no new neurological complications and no decline in cognitive function. This trend continued through 3 months, at which point there was no remaining evidence of HITS.

Multiple characteristics were associated with an increased frequency of HITS during TAVR but mean transaortic gradient at baseline was the only confirmed independent predictor after multivariate analysis.

Several Remaining Questions

“Collectively, these findings support the notion that the predominant etiology of periprocedural strokes during [TAVR] is embolic and that emboli consist of debris from the calcified, native aortic valve or from aortic arch atheromata which are common in the elderly patients undergoing [TAVR],” the authors write.

But because most lesions were seen during valve manipulation and the fact that mean transaortic gradient at baseline was the only independent predictor of HITS, “the aortic arch plays only a minor role for periprocedural stroke and the transapical may therefore not be superior to the transfemoral approach,” they note.

Dr. Kahlert and colleagues expected to see a higher rate of HITS with CoreValve because initial positioning is “rather quick and continuous adjustments are performed subsequently during stepwise release of the self-expandable stent-frame, whereas precise positioning prior to implantation is more time-consuming for correct placement of the [Sapien] valve,” they write. But the opposite was seen in the study, suggesting that possibly “the metallic stent-frame acts in a grater-like fashion scraping calcific debris from the native valve,” they add.

The study authors advise that these issues be dealt with in the development of next-generation TAVR devices, and that the new devices “offer repositionability and retrievability and require more extensive valve manipulation.”

Overall, the authors emphasize that the “clinical relevance of silent neuroimaging lesions and the high number of periprocedural microemboli still remains unclear, but must be resolved when the indication for [TAVR] is broadened to younger, lower-risk patients, since silent emboli have been associated with declining neurocognitive function and deterioration of dementia.”

Breaking Down the Procedure

In a telephone interview with TCTMD, Ted Feldman, MD, of Evanston Hospital (Evanston, IL), said the study “is another important building block in our understanding [of cerebral embolization during TAVR,] and it helps to segment the portions of the procedure that are most responsible for producing transcranial Doppler signals.”

While the findings can help researchers determine when the greatest risk of brain lesions occurs, “we still don’t know where clinical strokes come from,” he said. “This will help people who are working on embolization strategies to focus on the portions of the procedure that are inherently highest risk, but it still doesn’t nail down whether those devices will work.”

Going forward, Dr. Feldman said clinical trials are needed to test new embolic protection filters or deflection devices currently being developed. “We are understanding with greater and greater detail where the risks are, but it remains to be seen whether our first few strategies for diminishing these risks are going to be successful,” he concluded.

Study Details

No HITS were identified in any patients at baseline. Patients undergoing transapical TAVR had a higher logistic EuroSCORE than transfemorally treated patients, and diabetes was more frequent in patients undergoing transfemoral TAVR with Sapien.

 


Source:
Kahlert P, Al-Rashid F, Doettger P, et al. Cerebral embolization during transcatheter aortic valve implantation: A transcranial Doppler study. Circulation. 2012;Epub ahead of print.

 

 

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Cerebral Embolization During TAVR Comparable Across Access Routes, Devices

Cerebral microembolization is inherent to transcatheter aortic valve replacement (TAVR) but is not associated with increased neurological deficits or acutely impaired neurocognitive function, according to a study published online August 16, 2012, ahead of print in Circulation. In addition, no
Disclosures
  • Dr. Kahlert reports receiving honoraria from Edwards Lifesciences.
  • Dr. Feldman reports serving as a consultant for Abbott, Boston Scientific, and Edwards Lifesciences.

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