Distinct intra‐arterial clot localization affects tissue‐level collaterals and venous outflow profiles

Abstract

Background and purpose Arterial clot localization affects collateral flow to ischemic brain in patients with acute ischemic stroke due to large vessel occlusion (AIS‐LVO). We determined the association between vessel occlusion locations, tissue‐level collaterals (TLC), and venous outflow (VO) profiles and their impact on good functional outcomes. Methods We conducted a multicenter retrospective cohort study of consecutive AIS‐LVO patients who underwent thrombectomy triage. Baseline computed tomographic angiography (CTA) was used to localize vessel occlusion, which was dichotomized into proximal vessel occlusion (PVO; internal carotid artery and proximal first segment of the middle cerebral artery [M1]) and distal vessel occlusion (DVO; distal M1 and M2), and to assess collateral scores. TLC were assessed on computed tomographic perfusion data using the hypoperfusion intensity ratio. VO was determined on baseline CTA by the cortical vein opacification score. Primary outcomes were favorable VO and TLC; secondary outcome was the modified Rankin Scale after 90 days. Results A total of 649 patients met inclusion criteria. Of these, 376 patients (58%) had a PVO and 273 patients (42%) had a DVO. Multivariate ordinal logistic regression showed that DVO predicted favorable TLC (odds ratio [OR] = 1.77, 95% confidence interval [CI] = 1.24–2.52, p = 0.002) and favorable VO (OR = 7.2, 95% CI = 5.2–11.9, p < 0.001). DVO (OR = 3.4, 95% CI = 2.1–5.6, p < 0.001), favorable VO (OR = 6.4, 95% CI = 3.8–10.6, p < 0.001), and favorable TLC (OR = 3.2, 95% CI = 2–5.3, p < 0.001), but not CTA collaterals (OR = 1.07, 95% CI = 0.60–1.91, p = 0.813), were predictors of good functional outcome. Conclusions DVO in AIS‐LVO patients correlates with favorable TLC and VO profiles, which are associated with good functional outcome.

Cerebral venous outflow profiles are associated with the first pass effect in endovascular thrombectomy

“…VO robustness has been reported to be strongly dependent on the distinct localization of the arterial thrombus. 17 Thus, in the event of a more proximal vessel occlusion (eg, internal carotid artery or proximal M1 occlusions including the perforating branches), VO is expectedly hampered, presumably owing to the reduced amount of blood perpetrating the affected brain tissue, and lower COVES were reported for this group of patients. 17 We too found a strong collinearity between arterial clot localization and VO profiles (variance of inflation=7.34), with COVES becoming insignificant when adding arterial clot localization into the multivariable regression models.…”

“… 17 Thus, in the event of a more proximal vessel occlusion (eg, internal carotid artery or proximal M1 occlusions including the perforating branches), VO is expectedly hampered, presumably owing to the reduced amount of blood perpetrating the affected brain tissue, and lower COVES were reported for this group of patients. 17 We too found a strong collinearity between arterial clot localization and VO profiles (variance of inflation=7.34), with COVES becoming insignificant when adding arterial clot localization into the multivariable regression models. These observations consequently allow for the presumption that the assumed beneficial effects of favorable VO profiles on FPE (more robust tissue microperfusion and elevated ‘intravasal pressure’ distal to the thrombus) that we speculated on above, become strongly mitigated in the event of a more proximal vessel occlusion, which is in accordance with the deliberations of prior studies.…”

“…Both models were adjusted for variables showing significance in the univariate analysis, that is, time from symptom onset to reperfusion, and penumbra volume (Tmax >6 s). Owing to a reportedly strong inter-relation of arterial clot localization and VO profiles, 17 a variance of inflation analysis was conducted to investigate the covariance between arterial clot localizations and VO profiles in the respective regression models. Variance of inflation was found to be 7.34 and thus a high collinearity between VO and clot localization was assumed, which is in accordance with previous studies.…”

“…Variance of inflation was found to be 7.34 and thus a high collinearity between VO and clot localization was assumed, which is in accordance with previous studies. 17 Since the impact of clot localization on VO profiles has been investigated before and the primary focus of our analysis was to investigate the correlation between venous collateral biomarkers on FPE, we decided to exclude clot localization from the regression models under these circumstances, as it might introduce a high statistical bias to the interpretability of these models. Any unknown data were indicated at the given section below the tables.…”

Favourable arterial, tissue-level and venous collaterals correlate with early neurological improvement after successful thrombectomy treatment of acute ischaemic stroke

“…Interestingly, in one study, failure to achieve ENI was not associated with PAC status in a multivariable analysis,6 which differs slightly from our finding that robust PAC were associated with ENI. Our subsequent finding that robust PAC did not influence long-term functional outcome casts further uncertainty on the role of pial collaterals alone in ischaemic stroke recovery, and it suggests that TLC and VO may be more important variables in achieving long-term functional independence 16 24…”