In a subgroup of acute ischaemic stroke patients presenting with Alberta stroke program early CT score (ASPECTS) 0–5, who were treated with mechanical thrombectomy, successful reperfusion was found to be beneficial without increasing the risk of intracerebral haemorrhage. The corresponding study, recently published in Stroke, was carried out by Johannes Kaesmacher (Institute of Diagnostic and Interventional Neuroradiology) and Urs Fischer (Department of Neurology), University Hospital Bern, Switzerland, and colleagues from a large consortium.
Kaesmacher and colleagues put forward that the issue of whether ischaemic stroke patients presenting with low ASPECTS should be treated with mechanical thrombectomy remains “one of the most relevant unanswered questions in acute stroke treatment”. They set out to analyse the effect of successful reperfusion on functional outcome, mortality and symptomatic intracerebral haemorrhage. Through utilising the BEYOND-SWIFT registry (Bernese-European registry for ischaemic stroke patients treated outside current guidelines with neurothrombectomy devices using the Solitaire Fr with the intention for thrombectomy), the study investigators also aimed to assess the safety and efficacy of endovascular treated patients in this subgroup as compared to a group of patients presenting with ASPECTS 6–10.
Of the 1532 patients included from the retrospective, international, multicentre observational registry, 237 patients were ASPECTS 0–5 (mean age: 67.1±14.4 years), while 1295 were ASPECTS 6 or over. Further supporting the notion that treatment decisions regarding the former subgroup vary greatly, Kaesmacher and colleagues remark: “The proportion of patients treated with low ASPECTS scores differed significantly between participating centres.” Primary outcome was defined as modified Rankin Scale (mRS) 0–2 at 90 days, while secondary outcome included rates of 90-day mRS 0–2, 90-day mortality and the occurrence of symptomatic intracerebral haemorrhage.
Overall rates of favourable outcome and mortality at 90-days in the low ASPECTS subgroup were 40.1% (95/237) and 40.9% (97/237), respectively, while successful reperfusion was achieved in 69.9% of patients in this cohort. The authors report that successful reperfusion was associated with favourable clinical outcome (mRS 0–3; adjusted Odds Ratio [aOR] 5.534; 95% CI: 2.363–12.961), functional independence (mRS 0–2; aOR 5.583; 95% CI: 1.964–15.873), major early neurological improvement (aOR 11.635; 95% CI: 3.980–34.011), and reduced mortality (aOR 0.180; 95% CI: 0.083–0.390). Kaesmacher and colleagues ascertain that these effects remained significant after adjusting for imaging modality-associated variance, but were “less marked in patients presenting with ASPECTS 0–4”, as they say that only the effect on mortality remained significant here.
Furthermore, rates of symptomatic intracerebral haemorrhage were lower in successfully reperfused patients (aOR 0.235; 95% CI: 0.062–0.887). According to the authors, although interventions led to less successful reperfusion and tended to be more complicated in patients with ASPECTS 0–5 compared to those with ASPECTS 6–10, rates of symptomatic intracerebral haemorrhage remained comparable.
With regards to imaging modalities, Kaesmacher and colleagues note that the present analysis included both patients with CT (n=78) and with diffusion-weighted (n=154) ASPECTS. They recognised that “although diffusion-weighted ASPECTS is thought to be more sensitive in terms of detecting early ischaemic changes, it may also overestimate the final infarct core”. However, the study investigators did not find a significant interaction between the effect of successful reperfusion and the imaging modality that determined the ASPECTS score.
Alluding to particular limitations of the study, Kaesmacher et al say that most importantly, ASPECT scores were rated at each centre, hence were not core-lab adjudicated—meaning the validity may be compromised. Further, the low ASPECTS group was primarily supplied by three centres, “limiting the generalisability of the findings”. In summary, the study authors say: “Because of the retrospective, nonrandomised nature of the data and the lack of an untreated control group, our results should be viewed as hypothesis generating”.
Yet, Kaesmacher and colleagues maintain that the findings support the notion that rapid and complete reperfusion in large vessel occlusion acute ischaemic stroke patients is beneficial. “The data stress the need for a randomised controlled trial comparing the benefits of endovascular therapy versus best medical treatment in this subgroup of patients”. Moreover, as the study sheds light on the potential impact of the imaging modality used for ASPECTS and the associated outcomes, the authors further postulate that cut-offs for treatment are likely to be not directly comparable among centres using CT or MRI.