Set to be presented at the upcoming Society of Interventional Radiology (SIR) annual scientific meeting (23–28 March, Salt Lake City, USA), an anticipated late-breaking analysis of the BEST-CLI (Best endovascular versus best surgical therapy in patients with critical limb ischaemia) trial will expose the cause and significant impact that endovascular technical failure (ETF) had on patient outcomes. In doing so, the investigators hope to provide a granular, contextual understanding of why these failures happen in real-world practice.
Published in 2022, the BEST-CLI trial results found surgical intervention superior to endovascular revascularisation. Split into two cohorts based on the availability of suitable single segment greater saphenous vein (SSGSV) for bypass, BEST-CLI enrolees were randomised in a 1:1 fashion to either surgery with SSGSV bypass or endovascular treatment (cohort 1), or surgery with an alternate bypass conduit or endovascular treatment (cohort 2). Enrolment criteria required reasonable surgical risk and anatomy suitable for both bypass and endovascular treatment. The results showed that technical success was 98.3% vs. 84.7% for cohort 1, and 100% versus 80.6% in cohort 2, respectively.
Technical failure rates in both cohorts markedly contributed to the difference in outcome between surgery and endovascular outcomes in both groups, but the reason these failures occurred was unclear. This formed the basis for Richard Powell (Dartmouth Hitchcock Medical Center, Lebanon, USA) et al’s analysis which sought to evaluate the causes and impacts of ETF on outcomes.
Powell, speaking to Interventional News, explains that the BEST-CLI findings offered a close-to-accurate representation of real-world endovascular treatment experience. “If you look at a lot of studies carried out by industry there are very low rates of technical failure, as lower-risk patients are often cherry-picked for enrolment meaning biased results,” Powell states. However, in extracting causal factors of ETF from the BEST-CLI data, Powell et al have drawn conclusions which will “[confirm] suspicions” about industry-run studies in this arena.
In their analysis, Powell and colleagues analysed the causes for ETF in both cohorts, the impact on major adverse limb events (MALE), above ankle amputation, death and major adverse cardiovascular events (MACE: defined as myocardial infarction, stroke and serious cardiovascular adverse events). ETF was defined as the inability to successfully complete the initial endovascular procedure.
“We approached this with an open mind,” details co-investigator John Kaufman (Oregon Health and Science University [OHSU] in Portland, USA). “We were interested that proximal SFA [superficial femoral artery] occlusion, which was such an influential determinant, and that failure to cross the lesion was far more common than dissection, residual stenosis, or distal embolization as a failure mode.”
The investigators also analysed lesion location, which Powell highlights as a strength of their trial. In determining this, he hopes that granular predictions can be developed for patients that are less likely to achieve technical success, to map potential failure modes for each specific case.
Kaufman suspects there will be great interest in their findings set to be presented at highly-anticipated SIR 2024 in Salt Lake City, USA, due to the significant influence ETF had on outcomes in the BEST-CLI dataset, and on real-world endovascular practice. He adds that their results will likely stimulate even more questions in an attempt to elucidate the reasons for ETF even further. “We anticipate some difficult and maybe even some sceptical audience questions at the SIR annual meeting” he speculates.
Taking this in stride, Kaufman views that this is all an essential part of science and important research, but there are questions that they will not be able to answer yet, such as the morphology of uncrossable occlusions that cause ETF. “We don’t yet know whether these are flush or heavily calcified, nor the specifics of the techniques used to attempt to cross the lesions. I think we all approach occlusions with a measure of respect, and these results support that.”
Ahead of the presentation of their results, USA, Kaufman hopes to shed some light on the context for why ETF happens in order to help provide guidance when evaluating patients, and point to areas of improvement and innovation in endovascular procedures. In using the BEST-CLI data for their current research, Powell adds that credit is due to the three principal investigators—Matthew Menard (Brigham and Women’s Hospital, Boston, USA), Kenneth Rosenfield (Massachusetts General Hospital, Boston, USA), and Alik Farber (Boston Medical Center, Boston, USA)—who accomplished a “huge undertaking” with a highly comorbid and sick patient population, which produced valuable, real-world data for the betterment of endovascular treatment.
