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Background To investigate whether collateral status could modify the associations between post-thrombectomy blood pressure (BP) measures and outcomes. Methods and Results Patients with anterior-circulation large-vessel-occlusion successfully recanalized in a multicenter endovascular thrombectomy registry were enrolled. Pretreatment collateral status was graded and dichotomized (good/poor) in angiography. Maximum, minimum, and mean systolic BP (SBP) and BP variability (assessed by the SD, coefficient of variation) during the initial 24 hours after endovascular thrombectomy were obtained. The primary outcome was unfavorable 90-day outcome (modified Rankin Scale score 3-6). Secondary outcomes included symptomatic intracranial hemorrhage and 90-day mortality. Adjusted odds ratios (aOR) of BP parameters over the outcomes were obtained in all patients and in patients with good/poor collaterals. Among 596 patients (mean age 66 years; 59.9% males), 302 (50.7%) patients had unfavorable 90-day outcome. In multivariable analyses, higher mean SBP (aOR, 1.59 per 10 mm Hg increment; 95% CI, 1.26-2.02; P <0.001), mean SBP >140 mm Hg (versus ≤120 mm Hg; aOR, 4.27; 95% CI, 1.66-10.97; P =0.002), and higher SBP SD (aOR, 1.08 per 1-SD increment; 95% CI, 1.01-1.16; P =0.02) were respectively associated with unfavorable 90-day outcome in patients with poor collateral but not in those with good collateral. A marginal interaction between SBP coefficient of variation tertiles and collaterals on 90-day functional outcome ( P for interaction, 0.09) was observed. A significant interaction between SBP coefficient of variation tertiles and collaterals on 90-day mortality ( P for interaction, 0.03) was observed. Conclusions Higher postprocedural BP is associated with 90-day unfavorable outcomes after successful endovascular thrombectomy in patients with poor collateral. Registration URL: https://www.chictr.org.cn; Unique identifier: ChiCTR1900022154.

We aimed to investigate the roles of antegrade residual flow and leptomeningeal collateral flow in sustaining cerebral perfusion distal to an intracranial atherosclerotic stenosis (ICAS). Patients with apparently normal cerebral perfusion distal to a symptomatic middle cerebral artery (MCA)-M1 stenosis were enrolled. Computational fluid dynamics models were built based on CT angiography to obtain a translesional pressure ratio (PR) to gauge the residual antegrade flow. Leptomeningeal collaterals (LMCs) were scaled on CT angiography. Cerebral perfusion metrics were obtained in CT perfusion maps. Among 83 patients, linear regression analyses revealed that both translesional PR and LMC scale were independently associated with relative ipsilesional mean transit time (rMTT). Subgroup analyses showed that ipsilesional rMTT was significantly associated with translesional PR ( p  < 0.001) rather than LMC scale in those with a moderate (50-69%) MCA stenosis, which, however, was only significantly associated with LMC scale ( p  = 0.051) in those with a severe (70-99%) stenosis. Antegrade residual flow and leptomeningeal collateral flow have complementary effects in sustaining cerebral perfusion distal to an ICAS, while cerebral perfusion may rely more on the collateral circulation in those with a severe stenosis.

Collateral circulation plays a vital role in sustaining blood flow to the ischaemic areas in acute, subacute or chronic phases after an ischaemic stroke or transient ischaemic attack. Good collateral circulation has shown protective effects towards a favourable functional outcome and a lower risk of recurrence in stroke attributed to different aetiologies or undergoing medical or endovascular treatment. Over the past decade, the importance of collateral circulation has attracted more attention and is becoming a hot spot for research. However, the diversity in imaging methods and criteria to evaluate collateral circulation has hindered comparisons of findings from different cohorts and further studies in exploring the clinical relevance of collateral circulation and possible methods to enhance collateral flow. The statement is aimed to update currently available evidence and provide evidence-based recommendations regarding grading methods for collateral circulation, its significance in patients with stroke and methods under investigation to improve collateral flow., Competing Interests: Competing interests: None declared.

Objectives: Fractional flow reserve (FFR) accurately predicts the degree of stenosis and is now widely used to identify clinically significant severe coronary artery lesions. In the current study, we utilized a similar indicator, fractional flow (FF), to determine the hemodynamic impact of symptomatic intracranial atherosclerotic stenosis (ICAS) and to assess the correlation of FF with the severity of stenosis and collateral circulation., Methods: Patients with symptomatic ICAS (70-99% stenosis) confirmed on digital subtraction angiography (DSA) were consecutively recruited. FF was obtained during DSA examination with the use of pressure sensors and was measured as a ratio, comparing measurements distal to an ICAS lesion (Pd) and within the aorta (Pa). The degree of leptomeningeal collateralization was graded from zero (absent) to four (complete compensatory). The correlation between FF, anatomical stenosis, and collateral status was then analyzed., Results: Twenty-five patients with a mean age of 55.6 years were analyzed. The median percentage of stenosis and median FF were 82.3 and 0.68%, respectively. Eleven patients were found to have poor collateralization (grade 0-2), and fourteen patients were identified with good collateral circulation (grade 3-4). Overall, the hemodynamic impact of an atherosclerotic lesions worsened (decreased FF) as the percentage of stenosis increased, although this did not reach statistical significance (r = -0.398, p = 0.06). However, the status of collateralization significantly altered this correlation, worsening the hemodynamic impact in patients with poor collateral circulation (r = -0.677, p = 0.032). There was no difference in patients with good collateral circulation (r = -0.279, p = 0.356)., Conclusion: An anatomically severe (70-99%) symptomatic ICAS lesion may generate significant hemodynamic stress downstream as assessed by the indicator FF, particularly in patients with poor collateral circulation. Further, good collateralization may mitigate this hemodynamic impact, partially explaining the protective effect of collateral circulation against recurrent stroke in such patients.

Objective: We aimed to investigate the role of pretreatment collateral status in predicting the efficacy and safety of endovascular treatment (EVT) in acute ischaemic stroke due to cervical and/or cerebral arterial occlusions., Methods: Relevant full-text articles published since 1 January 2000, investigating correlations between collateral status and any efficacy or safety outcome in patients undergoing EVT in cohort or case-control studies, or randomised clinical trials, were retrieved by PubMed and manual search. Two authors extracted data from eligible studies and assessed study quality. Risk ratios (RR) were pooled for good versus poor collaterals for outcomes based on a random-effects model. Sensitivity and subgroup analyses were conducted., Results: In total, 35 (3542 participants) and 23 (2652 participants) studies were included in qualitative review and quantitative meta-analysis, respectively. Overall, good pretreatment collaterals increased the rate of favourable functional outcome at 3 months (RR=1.98, 95% CI 1.64 to 2.38; p<0.001), and reduced the risks of periprocedural symptomatic intracranial haemorrhage (RR=0.59, 95% CI 0.43 to 0.81; p=0.001) and 3-month mortality (RR=0.49, 95% CI 0.38 to 0.63; p<0.001), as compared with poor collaterals, in patients with acute ischaemic stroke under EVT. No individual study could alter the estimate of overall effect of collateral status, but there were moderate to significant heterogeneities between subgroups of studies with different modes of EVT, different arterial occlusions and different collateral grading methods., Conclusions: Good pretreatment collateral status is associated with higher rates of favourable functional outcome, and lower rates of symptomatic intracranial haemorrhage and mortality, in patients with acute ischaemic stroke receiving endovascular therapies., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Background: Pre-treatment collateral status may be associated with the rates of successful revascularization in acute ischemic stroke patients receiving endovascular treatment (EVT). We conducted a systematic review and meta-analysis to synthesize relevant evidence currently available., Methods: Relevant full-text articles published in English since January 1, 2000, reporting associations between collateral status and successful reperfusion and/or recanalization in acute ischemic stroke patients receiving EVT in cohort or case-control studies, or randomized clinical trials, were retrieved through search of PubMed. Study selection, data extraction and study quality assessment were carried out by 2 investigators. Risk ratios (RR) were pooled for good vs. poor collaterals for the outcomes of successful reperfusion and recanalization, based on random-effects models. Subgroup analyses were conducted to explore for potential factors that might interfere with the effects of pre-treatment collateral status on reperfusion by EVT., Results: In total, 27 studies (2,366 subjects) were included in qualitative analysis, among which 24 studies (2,239 subjects) were quantitatively analyzed. Overall, good pre-treatment collaterals significantly increased the rate of both successful reperfusion (RR 1.28, 95% CI 1.17-1.40; p < 0.001) and recanalization (RR 1.23, 95% CI 1.06-1.42; p = 0.006), as compared with poor collaterals. Subgroup analyses revealed that the effects of collateral status on successful reperfusion by EVT might be different between populations with different ethnicities., Conclusions: Good pre-treatment collaterals may enhance the rates of successful reperfusion and recanalization in EVT for acute ischemic stroke. This may partly explain the favorable effects of good pre-treatment collaterals on clinical outcomes of stroke patients receiving EVT. Thus, it would be valuable to assess the collateral status prior to EVT in acute ischemic stroke. But studies are needed to further verify if the positive effects of good collaterals on revascularization by EVT are restricted to certain subgroups of patients., (© 2015 S. Karger AG, Basel.)

Background: Stroke caused by acute basilar artery occlusion (BAO) is devastating with high dependency and mortality. Recent trials have demonstrated the efficacy of endovascular treatment (EVT) for acute BAO, while pretreatment collaterals may be a valuable prognostic indicator for post-EVT outcomes. Aims: To systematically review and synthesize evidence on the associations between pretreatment collateral status and outcomes after EVT in acute BAO. Methods: We retrieved relevant full-text articles published in English since 1 January 2010, reporting associations between pretreatment collateral status and outcomes after EVT for BAO, by searching MEDLINE and Embase. The primary outcome was favorable or good 90-day functional outcome (modified Rankin Scale [mRS] 0–2 or 0–3); secondary outcomes included successful recanalization, symptomatic intracranial hemorrhage, final infarct volume, and 90-day mortality. Risk ratios (RRs) with 95% confidence intervals (CIs) for good versus poor collaterals on the outcomes were synthesized using random-effects models. Subgroup and sensitivity analyses were conducted for the primary outcome. Results: Overall, 29 primary studies (2995 participants) were included in qualitative review, among which 16 studies (1447 participants) were meta-analyzed. With different imaging modalities and methods to grade the collateral status, good collaterals were found in 33–85% of patients in the individual primary studies (I2 = 95.2%, p < 0.001), with a pooled proportion of 51% (95% CI: 40–62%) across all studies. Good pretreatment collaterals were associated with a doubled rate of favorable/good 90-day functional outcome (RR = 2.03, 95% CI: 1.63–2.51, p < 0.001), a higher rate of successful recanalization (RR = 1.23, 95% CI: 1.04–1.45, p = 0.015), and reduced 90-day mortality (RR = 0.59, 95% CI: 0.43–0.81, p = 0.001) after EVT for BAO. None of the primary studies reported the associations of good collaterals with the other secondary outcomes. Subgroup analyses revealed possibly more prominent protective effect of good pretreatment collaterals over the primary outcome, in studies with longer time windows in patient eligibility criteria for EVT (p = 0.028 for between-subgroup heterogeneity). Conclusions: In patients with BAO receiving EVT, good pretreatment collateral status was associated with a higher chance of favorable 90-day functional outcome, despite the various methods in grading the collateral circulation. Efforts are needed for more standardized collateral assessment in BAO, for more reliable and generalizable investigations of its clinical implications. [ABSTRACT FROM AUTHOR]