As evidence builds on the importance of reducing the risk of stroke by removing residual air prior to thoracic endovascular aortic repair (TEVAR) procedures, the onus will be on surgeons and device manufacturers to minimize this risk, attendees of CX Aortic Vienna 2021 (Oct. 5–7, broadcast) heard. The claim came in a discussion focused on findings from the STEP (Stroke from thoracic endovascular procedures) study, and featured a first-to-podium presentation highlighting the benefits of carbon dioxide compared to standard saline flushing after TEVAR.
Tilo Kölbel, MD, of Hamburg, Germany, began this session by introducing the problem of cerebral damage following both TEVAR and transcatheter aortic valve implantation (TAVI) procedures—noting that the relatively low rate of postoperative stroke “does not tell the whole story,” as silent brain infarctions (SBIs) are far more prevalent and can lead to a range of neurological disorders later in life. He went on to detail that, while the source of stroke and SBIs is multifactorial, air embolisation caused by devices used in TEVAR and TAVI is one of the key contributors.
Following this, Fiona Rohlffs, MD, also of Hamburg, Germany, outlined the increased removal of residual air that can be achieved by introducing carbon dioxide to the standard, saline-based flushing technique often used in TEVAR, as well as the additional benefit of adding an extra flush port to the stent graft delivery system. She went on to report preliminary results from the STEP study, which included the first cohort in which carbon dioxide-flushed devices had been deployed in endovascular aortic arch repairs, noting an SBI incidence of about 50%—which compares favorably to the 80% rate reported in standard flushing without carbon dioxide.
Session moderator Markus Steinbauer, MD, of Regensburg, Germany, stated that the industry is now taking notice of this research into the importance of removing residual air prior to these procedures, with many companies that manufacture TEVAR devices currently attempting to introduce features like additional flush ports. This prompted Roger Greenhalgh, MD MChir, London, England, the session’s anchor, to claim that research from the STEP registry is paving the way for surgeons themselves to systematically consider how they can minimize stroke risks following thoracic endovascular procedures, before agreeing with Rohlffs that this is a multifactorial problem, and efforts to reduce liquid and solid embolization are also key.
Evidence on the potential benefit of introducing carbon dioxide into this complex picture was then compounded by Richard Gibbs, MD, also of London, England, who presented the results of a non-randomized, prospective study comparing carbon dioxide and standard saline flushing in 187 patients. Gibbs reported no difference in clinical stroke outcomes, but did highlight a significant reduction in the total number and surface area of new diffusion-weighted magnetic resonance imaging (DW-MRI) infarcts after carbon dioxide flushing. He concluded that patients are now being randomized across the United Kingdom, U.S., and New Zealand in a larger study designed to further examine this phenomenon.
More insight came from Wolf Eilenberg, MD, of Hamburg, Germany, who discussed the largest cohort study investigating cerebral microbleeds (CMBs) after TEVAR to date, in which 50% of patients presented with SBIs and 60% had CMBs—warranting further research, not only on the risk factors associated with CMBs, but also their long-term clinical impact. Greenhalgh echoed this view, describing these microbleeds as a “moving target” of which a greater understanding is needed. Referring more broadly to the growing body of evidence on post-TEVAR stroke, Greenhalgh concluded: “Those who are working on this subject are influencing the industry. And, the industry will do all it can, but surgeons will also have to do everything they can—it is a combined effort and, together, we are making progress.”