Comparison of Risk Factors, Safety, and Efficacy Outcomes of Mechanical Thrombectomy in Posterior vs. Anterior Circulation Large Vessel Occlusion

Abstract

Background and Purpose: It is believed that stroke occurring due to posterior circulation large vessel occlusion (PCLVO) and that occurring due to anterior circulation large vessel occlusion (ACLVO) differ in terms of their pathophysiology and the outcome of their acute management in relation to endovascular mechanical thrombectomy (MT). Limited sample size and few randomized controlled trials (RCTs) with respect to PCLVO make the safety and efficacy of MT, which has been confirmed in ACLVO, difficult to assess in the posterior circulation. We therefore conducted a meta-analysis to study to which extent MT in PCLVO differs from ACLVO. Materials and Methods: We searched the databases PubMed, Cochrane, and EMBASE for studies published between 2010 and January 2021, with information on risk factors, safety, and efficacy outcomes of MT in PCLVO vs. ACLVO and conducted a systematic review and meta-analysis; we compared baseline characteristics, reperfusion treatment profiles [including rates of intravenous thrombolysis (IVT) and onset-to-IVT and onset-to-groin puncture times], recanalization success [Thrombolysis In Cerebral Infarction scale (TICI) 2b/3], symptomatic intracranial hemorrhage (sICH), and favorable functional outcome [modified Rankin Score (mRS) 0-2] and mortality at 90 days. Results: Sixteen studies with MT PCLVO (1,172 patients) and ACLVO (7,726 patients) were obtained from the search. The pooled estimates showed higher baseline National Institutes of Health Stroke Scale (NIHSS) score (SMD 0.32, 95% CI 0.15-0.48) in the PCLVO group. PCLVO patients received less often IVT (OR 0.65, 95% CI 0.53-0.79). Onset-to-IVT time (SMD 0.86, 95% CI 0.45-1.26) and onset-to-groin puncture time (SMD 0.59, 95% CI 0.33-0.85) were longer in the PCLVO group. The likelihood of obtaining successful recanalization and favorable functional outcome at 90 days was comparable between the two groups. PCLVO was, however, associated with less sICH (OR 0.56, 95% CI 0.37-0.85) but higher mortality (OR 1.92, 95% CI 1.46-2.53). Conclusions: This meta-analysis indicates that MT in PCLVO may be comparably efficient in obtaining successful recanalization and 90 day favorable functional outcome just as in ACLVO. Less sICH in MT-treated PCLVO patients might be the result of the lower IVT rate in this group. Higher baseline NIHSS and longer onset-to-IVT and onset-to-groin puncture times may have contributed to a higher 90 day mortality in PCLVO patients.

Keywords: Ischemic Stroke; Large Vessel Occlusion; Mechanical Thrombectomy/Endovascular treatment; acute ischemic stroke; anterior circulation; endovascular stroke treatment; endovascular thrombectomy; large vessel occlusion; mechanical thrombectomy; posterior circulation.

Figure 1

Preferred Reporting Item for Systematic Reviews and Meta-Analysis (PRISMA) flow diagram showing study selection (27).

Figure 2

Forest plot comparing “age” of patients with large vessel occlusion in the posterior circulation (PC) vs. anterior circulation (AC) who were treated with endovascular mechanical thrombectomy. Chi², chi-square statistic; CI, confidence interval; df, degrees of freedom; I², I-square heterogeneity statistic; IV, weighted mean difference; P, p-value; SD, standard deviation; Std., standardized; Tau², estimated variance of underlying effects across studies; Z, Z statistic.

Figure 3

Forest plot comparing the baseline characteristic “female sex” of patients with large vessel occlusion in the posterior circulation (PC) vs. anterior circulation (AC) who were treated with endovascular mechanical thrombectomy. Chi², chi-square statistic; CI, confidence interval; df, degrees of freedom; I², I-square heterogeneity statistic; M-H, Mantel–Haenszel statistic; P, p-value; Tau², estimated variance of underlying effects across studies; Z, Z statistic.

Figure 4

Forest plot comparing “admission NIHSS” of patients with large vessel occlusion in the posterior circulation (PC) vs. anterior circulation (AC) who were treated with endovascular mechanical thrombectomy. Chi², chi-square statistic; CI, confidence interval; df, degrees of freedom; I², I-square heterogeneity statistic; IV, weighted mean difference; P, p-value; SD, standard deviation; Std., standardized; Tau², estimated variance of underlying effects across studies; Z, Z statistic.

Figure 5

Forest plot comparing rate of intravenous thrombolysis in patients with large vessel occlusion in the posterior circulation (PC) vs. anterior circulation (AC) who were treated with endovascular mechanical thrombectomy. Chi², chi-square statistic; CI, confidence interval; df, degrees of freedom; I², I-square heterogeneity statistic; M-H, Mantel–Haenszel statistic; P, p-value; Tau², estimated variance of underlying effects across studies; Z, Z statistic.

Figure 6

Forest plot comparing “onset-to-intravenous thrombolysis time” in patients with large vessel occlusion in the posterior circulation (PC) vs. anterior circulation (AC) who were treated with endovascular mechanical thrombectomy. Chi², chi-square statistic; CI, confidence interval; df, degrees of freedom; I², I-square heterogeneity statistic; IV, weighted mean difference; P, p-value; SD, standard deviation; Std., standardized; Tau², estimated variance of underlying effects across studies; Z, Z statistic.

Figure 7

Forest plot comparing “onset-to-groin puncture time” in patients with large vessel occlusion in the posterior circulation (PC) vs. anterior circulation (AC) who were treated with endovascular mechanical thrombectomy. Chi², chi-square statistic; CI, confidence interval; df, degrees of freedom; I², I-square heterogeneity statistic; IV, weighted mean difference; P, p-value; SD, standard deviation; Std., standardized; Tau², estimated variance of underlying effects across studies; Z, Z statistic.

Figure 8

Forest plot of main and subgroup analyses comparing “successful recanalization” defined as thrombolysis in cerebral infarction scale (TICI) 2/3 in patients with large vessel occlusion (LVO) in the posterior circulation (PC) vs. anterior circulation (AC) who were treated with endovascular mechanical thrombectomy. Three studies with <20 PCLVO patients and/or patient recruitment primarily until 2012 were excluded from subgroup analysis. Chi², chi-square statistic; CI, confidence interval; df, degrees of freedom; I², I-square heterogeneity statistic; M-H, Mantel–Haenszel statistic; P, p-value; Tau², estimated variance of underlying effects across studies; Z, Z statistic.

Figure 9

Forest plot comparing “symptomatic intracranial hemorrhage” in patients with large vessel occlusion (LVO) in the posterior circulation (PC) vs. anterior circulation (AC) who were treated with endovascular mechanical thrombectomy. Two studies with <20 PCLVO patients and/or patient recruitment primarily until 2012 were excluded from subgroup analysis. Chi², chi-square statistic; CI, confidence interval; df, degrees of freedom; I², I-square heterogeneity statistic; M-H, Mantel–Haenszel statistic; P, p-value; Z, Z statistic.

Figure 10

Forest plot comparing “favorable functional outcome (defined as modified Rankin Scale score 0–2) at 90 days” in patients with large vessel occlusion (LVO) in the posterior circulation (PC) vs. anterior circulation (AC) who were treated with endovascular mechanical thrombectomy. Three studies with <20 PCLVO patients and/or patient recruitment primarily until 2012 were excluded from subgroup analysis. Chi², chi-square statistic; CI, confidence interval; df, degrees of freedom; I², I-square heterogeneity statistic; M-H, Mantel–Haenszel statistic; P, p-value; Tau², estimated variance of underlying effects across studies; Z, Z statistic.

Figure 11

Forest plot comparing “mortality at 90 days” in patients with large vessel occlusion (LVO) in the posterior circulation (PC) vs. anterior circulation (AC) who were treated with endovascular mechanical thrombectomy. Four studies with <20 PCLVO patients and/or patient recruitment primarily until 2012 were excluded from subgroup analysis. Chi², chi-square statistic; CI, confidence interval; df, degrees of freedom; I², I-square heterogeneity statistic; M-H, Mantel–Haenszel statistic; P, p-value; Tau², estimated variance of underlying effects across studies; Z, Z statistic.