Study Provides Insight Into Cerebral Embolization During TAVR

Embolic protection devices capture debris in the vast majority of transcatheter aortic valve replacement (TAVR) cases, according to a small, single-center study published in the April 27, 2015, issue of JACC: Cardiovascular Interventions. Risk of embolization is higher in patients receiving balloon-expandable valves or with a greater degree of oversizing.

Nicolas M. Van Mieghem, MD, and colleagues at Erasmus Medical Center (Rotterdam, the Netherlands), analyzed debris collected by the Montage dual filter embolic protection device (Claret Medical; Santa Rosa, CA) in 81 patients who underwent TAVR with the balloon-expandable Sapien XT valve (Edwards Lifesciences; n = 24) or the self-expanding CoreValve (Medtronic; n = 46) or Portico (St. Jude Medical; n = 1) valves. Patients were treated between December 2011 and December 2013.Take Home: Study Provides Insight Into Cerebral Embolization During TAVR

The cohort displayed substantial aortic root calcification, with a median Agatston score of 3,000. Most procedures (93%) were performed via the transfemoral route. Balloon predilation was routine (90%), and postdilation was required in more than one-quarter of cases. Filter devices were deployed in the brachiocephalic trunk and left common carotid artery.

Debris Common

Debris was captured in 86% of patients, with a mean size of 1 mm and ranging from 0.1 to 9.0 mm. Thrombotic material was found in 74% of patients and tissue-derived debris in 63%. Embolized tissue was derived from the native aortic valve leaflets, aortic wall, or left ventricular myocardium.

Tissue-derived debris was more commonly observed in patients implanted with balloon-expandable rather than self-expanding valves (79% vs 56%; P = .05). However, there was no difference in the odds of finding thrombotic material between the valve types.

Multivariate logistic regression analysis showed that use of balloon-expandable valves and greater cover index (a surrogate for valve oversizing) were independently associated with increased risk of tissue embolization (table 1). Valve area, comorbid PAD, and use of post-dilation did not appear to influence risk.

 Table 1. Independent Predictors of Tissue Embolization

One patient had a TIA at 1 week after successful CoreValve implantation during an episode of new-onset A-fib. In addition, 2 patients experienced disabling stroke—1 immediately after TAVR with CoreValve complicated by pericardial effusion and 1 after TAVR with Sapien XT complicated by valve embolization and rescue CoreValve implantation. Both patients ultimately died of multiorgan failure. Overall mortality at 30 days was 3%.

Ongoing Stroke Risk?

The study is the first to describe the debris that ends up in embolic filters during TAVR and provide information on its origin, Eugene Blackstone, MD, of the Cleveland Clinic (Cleveland, OH), told TCTMD in an email.

While filters capture most of the debris released during TAVR, some still reaches the brain. In an accompanying editorial, Josep Rodés-Cabau, MD, and Rishi Puri, MBBS, PhD, of the Quebec Heart and Lung Institute (Quebec City, Canada), note that, of all the percutaneous cardiac interventions, TAVR is associated with the highest stroke rate. It averages about 3% within the 30 days following the procedure in large registries and hovers around 4% to 5% in the 2 randomized trials in high-risk patients, they report.

“When it comes to frank strokes (and transient ischemic attacks) after TAVR, [few] are related to the time of the procedure,” Dr. Blackstone said. “There is an ongoing substantial risk of stroke for the rest of these patients’ lives.”

Although older patients already have a heightened stroke risk, it may be exacerbated by the presence of the prosthesis or leakage around it, he explained, adding, “Brain imaging changes being reported do not necessarily translate into clinical strokes, but many of us worry that with every loss of brain cells, some subclinical degradation of cognitive, behavior, motor, or other important brain functions occurs.”

Value of Embolic Protection Being Tested

Dr. Blackstone said he doubts that TAVR with newer devices will produce less debris. “With any type of TAVR, the diseased and often calcified native aortic cusps are ‘pushed’ out of the way to make room for a prosthetic device to be inserted,” he said. “To the extent that this process produces embolic debris, [it] would be continued unabated.”

There is still a place for surgical aortic valve replacement in reducing stroke risk, Dr. Blackstone noted, also urging continued research into embolic protection devices.

Drs. Rodés-Cabau and Puri report in the editorial that, to date, 2 pilot studies have demonstrated the feasibility and safety of using deflection devices in TAVR but both failed to show a reduction in brain lesions compared with historical controls. More encouragingly, the prospective, randomized CLEAN-TAVI trial demonstrated the ability of the Montage embolic protection device to lower both the volume and number of new brain lesions post-TAVR, they point out. However, they caution, “the utility of such devices as an adjunct during TAVR will ultimately depend on their ability to lower clinically meaningful endpoints in a cost-effective manner.”

In PARTNER I, use of transapical TAVR as an alternative access route did not lower the risk of early stroke, Dr. Blackstone noted. Another strategy favored by some, he added, is “pharmacologic protection against what is thought to be inevitable debris going to the brain.” Similarly, the editorial calls for prospective evaluation of various types and intensities of periprocedural anticoagulation during TAVR.

Questions Remain

“These data represent a good start at trying to understand the relative importance of debris during TAVR and how a cerebral filter may reduce the risk of stroke,” Isaac George, MD, of NewYork-Presbyterian/Columbia Medical Center (New York, NY), told TCTMD in an email. But, he added, the “sample size is small, and the cohort includes both balloon-expandable and self-expanding valves, which dilutes the ability to [draw] any substantial conclusions.”

Unanswered questions include whether it is worth the time and cost of placing a filter when third-generation devices may have stroke rates approaching 1% and whether certain valves carry a higher risk of debris or stroke than others, Dr. George commented.

 


Sources:
1. Van Mieghem NM, El Faquir N, Rahhab Z et al. Incidence and predictors of debris embolizing to the brain during transcatheter aortic valve implantation. J Am Coll Cardiol Intv. 2015;8:718-724.
2. Rodés-Cabau J, Puri R. Filtering the truth behind cerebral embolization during transcatheter aortic valve replacement [editorial]. J Am Coll Cardiol Intv. 2015;8:725-727.

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Disclosures
  • Dr. Van Mieghem reports receiving research grants from Claret Medical.
  • Dr. Blackstone reports serving as a primary investigator for the PARTNER trial, which was funded by Edwards Lifesciences.
  • Drs. George and Puri report no relevant conflicts of interest.
  • Dr. Rodés-Cabau reports receiving research grants from Edwards Lifesciences and Keystone Heart.

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