Mausaminben Hathidara, MD
Mechanical thrombectomy (MT) for patients with large vessel occlusion of anterior circulation, presenting within 6 hours from symptoms onset and ASPECT score 6-10, is the standard of treatment and recommended by the American Stroke Association. However, very limited data is available regarding safety and efficacy for such treatment modalities for patients with ASPECT score 0-5. This multicenter retrospective non-randomized study analyzed MT outcome for patients with ASPECT score 0-5 at 90 days. Primary outcome of the study was favorable outcome (mRS 0-3) at 90 days and secondary outcome was mRS 0-2 at 90 days, major early neurological improvement (defined as change in NIHSS >8 points, 24 hr NIHSS<1), all-cause mortality at 90 days and symptomatic intracerebral hemorrhage (sICH). 1532 patients who had confirmed anterior circulation LVO including intracranial ICA, ICA T/L, M1, M2, tandem occlusion and ASPECT score available on either CT (910/1532) or MRI (600/1532) were included in the final analysis. TICI score and ASPECT score were determined by an independent research fellow at each site. 90 days mRS was obtained by a physician or trained certified nurse. NIHSS at admission and 24 hours was performed by a stroke neurologist.
Out of 1532 patients, 1295 patients had ASPECT score 6-10 and 237 patients had ASPECT score 0-5. Out of those 237, 93 presented with ASPECTS 5, 60 with ASPECTS 4, and 84 with ASPECTS 0–3. Overall rates of favorable outcome (mRS ≤3) and mortality at day 90 were 40.1% (N=95/237) and 40.9% (N=97/237). Early neurological improvement was observed in 21.2% (N=32) of 151 patients for whom 24 hours NIHSS was available. Univariable comparison revealed successfully reperfused patients (TICI2b and TICI 3) had superior outcome. Even after adjusting for prespecified clinical confounders, results remained significant for reperfusion associated clinical favorable outcome (mRS 0-3, aOR 5.534; 95% CI, 2.363–12.961), functional independence (mRS score 0-2, aOR, 5.583; 95% CI, 1.964–15.873) and 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 ). Furthermore, it is important to note that sICH were lower in successfully reperfused patients (aOR, 0.235; 95% CI, 0.062– 0.887). There was more favorable outcome in the patients selected by MRI than CT; therefore, in final analysis, DWI-ASPECTS was increased by 1 point to estimate corresponding NCCT-ASPECTS as previously suggested by the SAMURAI registry.1 Even after applying logistic regression output by strata of admission imaging, a significant effect of reperfusion was still observed for mRS score 0–3 and mortality in both subgroups; however, uncertainty increased considerably (especially for CT). In a sub-cohort of patients with successful reperfusion, achieving TICI 3 instead of only TICI 2b was found to result in additional benefit. When analyses were confined to patients with ASPECTS 0–4 (N=144), the positive association between successful reperfusion and the outcome variables remained statistically significant only for mortality (aOR, 0.168; 95% CI, 0.056–0.499).
In short, this study suggests patients with ASPECT score 4 and 5 (based on image modality) functional independence (mRS 0-2) was overall 25% patients at 90 days especially when reperfusion was achieved. Successful reperfusion was independently associated with better outcome; however, reperfusion rates were lower compared to the group of ASPECT score 6-10, there was longer groin to reperfusion time, more perioperative complications, patients were younger and more often had proximal occlusion. This study at least reassures regarding safety of MT for these groups showing successful reperfusion did not result in sICH despite abrupt restoration of blood flow in large core, which is also suggested by other studies.2 Interrater reliability and accuracy of ASPECT score is debatable and raises the question of validity of these findings. In addition, since more of the patients with better outcome with ASPECT 5 were on DWI-ASPECT score than CT, it alludes the discussion whether DWI overestimates the core as previously suggested by the SAMURAI registry. When feasible, obtaining CT perfusion or MR perfusion for patients with lower ASPECT score and within 6 hours of presentation would be helpful before treatment decisiond with intervention. A multicenter prospective randomized trial is needed to overcome this limitation, as well as confirm the above suggested findings.
References:
- Nezu T, Koga M, Nakagawara J, Shiokawa Y, Yamagami H, Furui E, et al. Early ischemic change on CT versus diffusion-weighted imaging for patients with stroke receiving intravenous recombinant tissue-type plas- minogen activator therapy: stroke acute management with urgent risk- factor assessment and improvement (SAMURAI) rt-PA registry. Stroke. 2011;42:2196–2200. doi: 10.1161/STROKEAHA.111.614404
- Wang DT, Churilov L, Dowling R, Mitchell P, Yan B. Successful recanalization post endovascular therapy is associated with a decreased risk of intracranial haemorrhage: a retrospective study. BMC Neurol. 2015;15:185. doi: 10.1186/s12883-015-0442-x
