Embolic Debris Captured by Filters in Three-Quarters of TAVR Patients

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In patients undergoing transcatheter aortic valve replacement (TAVR), a dual-filter embolic protection device enables the capture of debris traveling to the brain in 75% of cases, according to findings published online May 7, 2013, ahead of print in Circulation.

Researchers led by Nicolas M. Van Mieghem, MD, of Erasmus Medical Center (Rotterdam, The Netherlands), analyzed 40 consecutive patients with severe aortic stenosis who underwent TAVR with the use of a dual filter-based embolic protection device (Montage Dual Filter System; Claret Medical, Santa Rosa, CA) between December 2011 and September 2012.

The device, which obtained CE mark approval for TAVR usage in October 2011, delivers 2 conically-shaped filters mounted onto a nitinol self-expanding wire frame within a single catheter to protect the cerebral vascular circulation. Patients received primarily the CoreValve prosthesis (90%; Medtronic, Minneapolis, MN), but some were implanted with the Sapien device (10%; Edwards Lifesciences, Irvine, CA).

Type of Debris Varies

Overall TAVR procedural success was obtained in all but 1 patient, and all embolic protection devices were successfully retrieved. Macroscopic debris was found in 1 or both filters in 75% of cases, varying in size between 0.15 mm and 4.0 mm (table 1).

Table 1. Captured Macroscopic Debris by Type

 
Foreign body material consistent with polymer, likely from one of the many catheters used during the TAVR procedure, was present between the fibrin of 4 patients.

One patient died within 30 days (2.5%); major vascular complications and life-threatening bleeding complications both occurred at a rate of 10%. One patient had a TIA at 6 days post-procedure.

Considering an Embolic Protection Strategy

“As TAVR technology shifts towards a lower risk and thus likely a younger patient population, the need to address and reduce cerebrovascular embolization becomes more urgent,” Dr. Van Mieghem and colleagues write. “Centers may therefore consider adoption of an embolic protection strategy to reduce the cerebral burden of procedure-related valvular embolic debris.”

In addition, the “high prevalence” of thrombotic material suggests “a need for more reliable anticoagulation protocols, balancing between the risk for thromboembolic and bleeding complications,” they continue, adding that newer anticoagulants and better follow-up may lead to a reduction in embolic debris.

Effect on Clinical Outcomes to Be Determined

In a telephone interview with TCTMD, Juan F. Granada, MD, of the CRF Skirball Research Center (Orangeburg, NY), praised Dr. Van Mieghem and colleagues for their well-conducted research that “elucidate[s] some of the mechanisms responsible for the embolization occurring during TAVR.

“What this study confirms from the histopathology point of view is that embolization is an event that occurs relatively frequently and that the nature of the embolic material is multifactorial and is a combination of the type of valve treated, the aortic wall composition, plus the potential thrombogenic effect related to device manipulation,” he explained.

Dr. Granada said the information regarding embolic composition was most fascinating but expressed surprise as to the size of the particles captured and the extent of material embolized from the vessel wall as well as the valve itself.

“Essentially it’s telling us that embolic events for TAVR patients [are unlikely to] be significantly impacted or improved with aggressive anticoagulation therapies. Most of these embolization events are related to mechanical dislodgement of debris and could be potentially prevented by improving valvular preparation and deployment technique as well as further development of filter and deflection devices,” he added. Still, whether or not using a filter is “going to have an impact on clinical practice or the way we do the procedure is to be determined,” Dr. Granada said

Future studies should focus on the incidence of clinical events related to the degree of embolization, he suggested. “Further research should be directed toward the development of better pre-dilatation techniques, better devices that produce less trauma at the time of deployment, and technologies that can prevent these events from occurring,” Dr. Granada concluded.

Study Details

Mean patient age was 77 years, and just over half (56%) were male. Approximately two-thirds of patients were on antiplatelet therapy, and one-quarter of patients were on anticoagulant therapy at baseline. Most access was transfemoral (90%). Balloon post dilatation was performed in 30% of procedures.

 

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Source:
Van Mieghem NM, Schipper MEI, Ladich E, et al. Histopathology of embolic debris captured during transcatheter aortic valve replacement. Circulation. 2013;Epub ahead of print.

 

 

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