In patients with large vessel occlusion (LVO) stroke caused by intracranial atherosclerotic stenosis (ICAS), rescue stenting following mechanical thrombectomy appears to lead to higher rates of successful reperfusion and 90-day functional independence—but also an increased occurrence of procedural complications—as compared to thrombectomy alone. These are among key findings of the RESCUE-ICAS registry, from which results were recently presented for the first time at the 2024 Society of Vascular and Interventional Neurology (SVIN) annual meeting (20–22 November, San Diego, USA).
Delivering these late-breaking data at SVIN 2024, Sami Al Kasab (Medical University of South Carolina, Charleston, USA) initially noted that, while the overwhelming majority of LVO strokes are understood to be ‘embolic’ in nature, roughly 10–30% are caused by underlying ICAS—and thrombectomy is believed to be a less effective treatment approach in this smaller subset of patients due to high re-occlusion rates in close to 50% of cases. With this in mind, RESCUE-ICAS—an international, multicentre, observational, prospective cohort study—sought to evaluate the prevalence of ICAS-LVO in western patient populations, understand neurointerventionists’ approach to ICAS-LVO, and compare thrombectomy with versus without rescue stenting in ICAS-LVO patients undergoing the procedure across 25 centres in the USA, Europe and Asia.
The registry defined ICAS-LVO as those cases in which there was 50–99% residual stenosis following any number of attempted thrombectomy passes, either with or without intraprocedural re-occlusion, with ICAS-LVO being identified intra-procedurally. It enrolled adult patients presenting within 24 hours of symptom onset with an emergent anterior- or posterior-circulation LVO and a National Institutes of Health stroke scale (NIHSS) score ≥6. And, as reported by Al Kasab, acute management of ICAS-LVOs took place at the discretion of the individual participating sites due to the observational nature of the registry.
“The study exposure was receiving a stent [following unsuccessful thrombectomy] versus thrombectomy alone, and patients who received balloon angioplasty alone were considered in the thrombectomy group,” the presenter stated. “We had 11 patients in the study who had an attempted stent placement that failed due to complication, perforation, dissection or inability to deliver the stenting construct. These patients were counted in the stenting group, in order to be consistent with the intention-to-treat analysis of a randomised trial.”
The primary endpoint for RESCUE-ICAS was 90-day functional independence measured via an mRS score of 0–2. Secondary endpoints included rates of final, successful reperfusion at the end of the procedure, symptomatic intracranial haemorrhage (ICH) and 90-day mortality. The registry collected data on patients allocated to either thrombectomy plus stenting or thrombectomy alone. Inverse probability of treatment weighting (IPTW) was deployed to adjust for potential confounders when it came to analysing the registry’s primary endpoint. Here, Al Kasab also noted that prespecified sensitivity analyses led the investigators to further stratify patients’ post-thrombectomy treatment modalities into the following groups: no stent or angioplasty; balloon angioplasty without stenting; self-expanding stent; and balloon-mounted stent.
“Between January 2022 and December 2023, about 6,000 patients underwent mechanical thrombectomy at the participating sites,” he continued. “Of those, 451 were identified as ICAS-LVO—and, of those, 417 were included in the final analysis, with 218 patients undergoing thrombectomy alone and 199 undergoing thrombectomy plus intracranial stenting.”
Regarding baseline demographics, Al Kasab reported no major differences in terms of average age or sex, nor premorbid mRS or occlusion location. However, patients in the stenting group were less likely to be non-Hispanic white (51.8% vs 62.4%; p=0.03), and less likely to have diabetes (33.2% vs 43.1%; p=0.037) or hyperlipidaemia (43.2% vs 56%; p=0.009).
Moving on to the registry’s key findings, he commented that patients in the non-stenting group saw a higher rate of intravenous thrombolysis (IVT)—27.5% compared to 18.6% in the stenting group (p=0.03)—while the average procedure duration was longer in the stenting group. In addition, as per the primary endpoint for RESCUE-ICAS, the rate of functional independence at 90 days was “significantly higher” in the stenting group (42.2%) compared to the non-stenting group (28.4%), backed by an adjusted odds ratio (OR) of 2.67 (95% confidence interval [CI], 1.66–4.32; p<0.001).
As per the registry’s most notable secondary endpoints, Al Kasab relayed that there was a higher rate of successful reperfusion (modified treatment in cerebral infarction [mTICI] score ≥2b) with stenting versus thrombectomy alone (90.9% vs 77.9%; p<0.001), as well as a greater frequency of 24-hour infarct volumes <30ml across a total of 260 patients with available magnetic resonance imaging (MRI) data in the stenting group (67.9% vs 50.3%; p=0.005). And, while there was also a higher overall complication rate in the stenting group (12.6% vs 5%; p=0.006), this ultimately did not translate into a statistically significant difference in the rate of symptomatic ICH between the two groups (9% vs 5.5%; p=0.162). All-cause mortality rates at 90 days were found to be statistically comparable with versus without stenting too (24.6% vs 30.7%; p=0.164), despite a trend towards reduced mortality in the stenting group.
“Commonly, you’re less likely to stent somebody who has a large core or difficult anatomy,” Al Kasab said, discussing the registry’s findings regarding stenting numbers across different sites. “But, here, there seems to be a pattern where some sites are heavy on stenting and some sites do not stent at all. Some sites stented zero patients with ICAS-LVO while some sites stented almost every ICAS-LVO patient.”
Touching in greater detail on data from the 260 patients who received an MRI within 24 hours, the presenter reported that the median final infarct volume was “significantly smaller” in the stenting group, adding that—as per mediation analyses—almost 50% of the effect of stenting on functional independence could be attributed to these lower 24-hour infarct volumes on MRI.
When assessing the registry’s primary endpoint across different intervention types, the investigators found that balloon angioplasty alone (25%) was associated with a similar rate of 90-day functional independence compared to thrombectomy alone (29%), while self-expanding stents (44.3%) and balloon-mounted stents (42.7%) both achieved statistically higher rates of functional independence. Via prespecified interaction analyses, Al Kasab and colleagues also determined that their aforementioned results favouring stenting remained consistent across occlusions located in the anterior- and posterior-circulations, and also with versus without the use of intravenous antiplatelets.
“This is a real-world, observational registry and prone to known bias—we need randomised data to look at the safety and efficacy of rescue stenting,” Al Kasab concluded.
Alongside Al Kasab’s presentation at the SVIN meeting, findings from RESCUE-ICAS have also been published in the journal Stroke.
