Mechanical thrombectomy appears to be a safe and technically feasible treatment option for ischaemic strokes caused by primary isolated anterior cerebral artery (ACA) occlusions in more distal locations. The procedure—which is more traditionally used in large vessel occlusions (LVOs) of the middle cerebral artery (MCA) and internal carotid artery (ICA)—has also demonstrated similar clinical outcomes to best medical management with or without intravenous thrombolysis (IVT).
These are the key findings of an international registry study published recently in the journal Radiology by Lukas Meyer (University Medical Center Hamburg-Eppendorf, Hamburg, Germany) et al.
As Meyer and his co-authors point out in their introduction, despite thrombectomy being a potential therapeutic option in distal occlusion stroke, current evidence supporting its benefits specifically for primary, isolated distal medium vessel occlusions (MeVOs) in the ACA is, to their knowledge, “generally unknown”.
They aimed to elucidate this issue through a case-control study of the TOPMOST registry—an international, retrospective, multicentre, observational registry of patients treated for distal cerebral artery occlusion stroke. Meyer et al analysed the clinical and safety outcomes of thrombectomy for primary, isolated ACA occlusions of the more distal A2–A4 segments, compared to best medical management with or without IVT, in daily clinical practice between January 2013 and October 2021.
In this study, endovascular reperfusion was evaluated using the modified thrombolysis in cerebral infarction (mTICI) scale. The number of reperfusion manoeuvres was counted—including first-pass effect (mTICI 3 after first attempt)—and a final reperfusion result of mTICI 2b–3 was considered a successful thrombectomy, with intervention times and the rate of intervention-related serious adverse events also being detailed.
Regarding clinical measures, early outcome was assessed via the median improvement of National Institutes of Health Stroke Scale (NIHSS) scores at 24 hours, while functional outcomes were defined as favourable (modified Rankin Scale [mRS] score of 0–2) or excellent (mRS 0–1) at 90 days. Safety was assessed by the occurrence of mortality—during hospitalisation and at day 90—as well as symptomatic intracerebral haemorrhages (ICHs).
From a total of 154 patients who met the inclusion criteria, Meyer et al detail that 110 patients (median age=76 years, 50 men) underwent propensity score matching, with 55 having received a thrombectomy and 55 receiving best medical management. Distal MVOs were located in the A2 (53% of patients), A3 (45%) and A4 (2%) segments.
Prior to propensity score matching, the authors observed a median time from symptom onset to groin puncture of 195 minutes across 94 patients who received a thrombectomy. The median number of reperfusion attempts was one, and successful thrombectomy (mTICI grade 2b–3) was achieved in 81% of patients. Complete reperfusion (mTICI 3) was achieved in 67% of patients—including a first-pass effect rate in 41%. Symptomatic and asymptomatic bleeding events were observed in 2% and 14% of patients, respectively, before propensity score matching.
The authors report a median 24-hour NIHSS point decrease of 2 in the thrombectomy cohort compared to 1 in the best medical management cohort. In addition, the distribution of mRS scores at 90 days showed “no evidence of a statistically significant difference” between the thrombectomy and non-thrombectomy cohorts regarding mRS scores of 0–1 (38% vs 33%, respectively) and 0–2 (49% in both groups).
“There was no evidence of statistically significant differences when clinical and safety outcomes were stratified by occlusion site,” Meyer et al add. “This finding remained stable if we included the last known mRS scores in patients with missing long-term follow-up.”
Functional outcomes stratified across several subgroups—including age, sex, occlusion site, NIHSS on admission, and whether IVT was given—showed no evidence of a difference in 90-day mRS score distributions between the two cohorts. Ninety-day mortality rates were similar with (22%) and without (31%) thrombectomy too, as were in-hospital mortality rates (11% and 10%, respectively).
“We did not find a treatment effect in favour of one therapy option after propensity matching,” Meyer et al conclude. “These results show the potential efficacy of [best medical management] in the subgroup of ACA distal medium vessel occlusion. Mechanical thrombectomy may be considered a technically feasible treatment option for acute ischaemic stroke due to primary isolated occlusions in the A2 and A3 segments because it can lead to high rates of successful reperfusion associated with favourable long-term outcome and did not result in increased rates of symptomatic bleeding events compared with [best medical management] if patients were treated at tertiary stroke centres.
“Nevertheless, patient selection for treatment allocation requires further investigation to identify patients who will benefit the most from available treatment options.”
And, in spite of their study’s potential limitations—including its retrospective design, small sample size, and absence of some clinical data—the authors assert that these results “reinforce clinical equipoise, and encourage ongoing and upcoming randomised trials investigating treatment options for distal MeVO stroke”.
