FROM JAMA
In patients undergoing transcatheter aortic valve implantation, use of a cerebral protection device to entrap and remove embolic debris reduced both the number and the size of ischemic brain lesions, according to a report published in JAMA.
The frequency and severity of postprocedure stroke symptoms were similar with and without the filter; however, the researchers noted that the study included only 100 patients and was not powered to assess differences in stroke rates.
Various cerebral protection devices were invented in response to the finding of a threefold increase in periprocedural stroke mortality following TAVI. Yet “clear evidence of the efficacy of any embolic protection device in TAVI is still missing,” said Stephan Haussig, MD, of the University of Leipzig (Germany) Heart Center, and his associates.
They performed a prospective randomized clinical trial at their center to assess the efficacy of the only cerebral protection device that was available when their study was designed. For the study, 100 patients with severe, symptomatic aortic stenosis were randomly assigned to undergo TAVI either with (50 patients) or without (50 patients) the use of a protective filter to capture embolic debris. The filter device was estimated to fully protect 74% of the brain and partially protect 24%, leaving only 2% unprotected.
The primary endpoint of the study was the number of ischemic brain lesions detected on diffusion-weighted MRI in the filter group, compared with the control group. This imaging was performed at baseline, 2 days after the procedure, and 7 days after the procedure.
In protected brain regions, the median number of new ischemic brain lesions was markedly lower in the filter group than in the control group (4 vs. 10) at 2 days, as well as at 7 days (3 vs. 7, respectively). In addition, the volume of new lesions in protected brain regions also was markedly lower in the filter group at 2 days (242 mm vs. 527 mm) and at 7 days (101 mm vs. 292 mm).
Similar protective effects were evident when the entire brain was evaluated. The median number of new lesions was markedly lower in the filter group than in the control group (8 vs. 16) at 2 days and at 7 days (5 vs. 10, respectively). The median lesion volume also was markedly lower in the filter group at 2 days (466 mm vs. 800 mm) and at 7 days (205 mm vs. 720 mm).
However, this protective effect didn’t translate into a substantive difference in neurologic outcomes between the two study groups, as assessed by the National Institutes of Health Stroke Scale and the modified Rankin scale. Five patients in each group developed symptoms of stroke, and all symptoms were deemed minor and nondisabling, the investigators said ( JAMA 2016;316[6]:592-601 ).
It is important to note that this study wasn’t powered to assess differences in stroke rates. Larger studies will be needed to assess the impact of protective devices on neurological and functional outcomes, Dr. Haussig and his associates wrote.
The two study groups also did not differ with regard to complications. Thirty-day mortality was 0% in the filter group and 2% in the control group, a nonsignificant difference.
The investigators pointed out that protective filter devices can protect the brain only while they are in place during TAVI, “which usually takes less than 1 hour and represents only 2% of the first 48 hours after which the first MRI was performed in this study. Based on the analyzed material captured and removed by the filters – e.g., old and fresh thrombus, endothelium, atheromatous plaque, valve tissue, and calcium – it becomes evident that causes of cerebral injury are multifactorial and that the embolic risk does not resolve immediately at the end of the TAVI procedure,” they said.
Perhaps the study’s most surprising finding was that nearly every patient had new cerebral lesions consistent with infarcts, but most of these were very small and not associated with any neurocognitive or functional impairments.
This study was limited in that it involved a single cardiac team assessing only one brand of filter device at a single hospital, so the results are not necessarily generalizable to a broader patient population or to the many other devices that have since been developed, Dr. Haussig and his associates added.
This study was funded by a grant from Claret Medical and Medtronic. Dr. Haussig reported having no relevant financial disclosures; his associates reported ties to numerous industry sources.
