Comparison of Superior and Inferior Division Occlusions Treated with Endovascular Thrombectomy

Feasibility and Clinical Outcome Predictors of Mechanical Thrombectomy in Distal Arterial Occlusion Causing Acute Ischemic Stroke: A Monocentric Retrospective Study

BACKGROUND

The feasibility and clinical outcome predictors of mechanical thrombectomy (MT) for strokes caused by distal arterial occlusion (DAO) remain the subject of debate.

METHODS

A retrospective analysis was conducted of patients with consecutive acute ischemic stroke treated using MT. Clinical and procedural-associated factors were studied to compare the efficacy, safety, and short-term and long-term outcomes of MT between the proximal arterial occlusion (PAO) and DAO groups. The predictors of a good functional outcome in the DAO group were also identified.

RESULTS

A total of 116 patients were included in this study, of whom 23 (19.8%) underwent MT for DAO. A higher complete recanalization rate was independently associated with PAO in adjusted models [adjusted odds ratio, 0.596; 95% CI, 0.377-0.941]. The measures of safety and clinical outcome showed no significant differences between the DAO and PAO groups. The National Institute of Health stroke scale (NIHSS) score on admission, hybrid technique use, and complete recanalization rate emerged as independent predictors of a good functional outcome in the DAO group.

CONCLUSIONS

The efficacy, safety, and short-term and long-term outcomes of DAO thrombectomy were similar to those of PAO thrombectomy. The good functional outcome predictors of MT in DAO included NIHSS on admission, hybrid technique use, and complete recanalization. Overall, the findings lead us to propose that MT may be considered a feasible option for treating DAO after a careful risk-benefit analysis.

Mechanical Thrombectomy in Medium Vessels Occlusion (MeVOs): An Institutional Experience with M2 Divisions of Middle Cerebral Artery

Background

Mechanical thrombectomy has been established as a safe, standard and effective treatment option for occlusions of the proximal segment of the middle cerebral artery (MCA), as demonstrated in numerous studies. However, performing thrombectomy in the M2 divisions of MCA presents inherent challenges. In this institutional experience, we aim to delineate the recanalisation rates achieved through mechanical thrombectomy in cases involving the M2 segment of the MCA.

Methods

We conducted a retrospective analysis of patients who underwent thrombectomy due to M2 MCA occlusions in the period from January 2018 to December 2021. Various factors affecting recanalisation rates were assessed.

Results

A total of 15 patients with M2 segment occlusions of the middle cerebral artery were included in the study, comprising 11 in the superior division and 4 in the inferior division. The successful recanalisation rate was 72.33%, with notably higher success observed in cases of inferior division occlusion. The primary outcome of our study was the mTICI recanalisation status, categorised as successful recanalisation (mTICI = 2b or mTICI = 3) and unsuccessful recanalisation (mTICI = 1 or mTICI = 2a) and mRS at 6 months. None of the predictors assessed reached statistical significance.

Conclusions

Mechanical thrombectomy demonstrates favourable efficacy and recanalisation rates in cases of M2 MCA division occlusion. Notably, inferior division occlusions exhibit a higher likelihood of successful recanalisation.

Defining the optimal size of an aspiration catheter in relation to the arterial diameter during mechanical thrombectomy for stroke

BACKGROUND

Mechanical thrombectomy for acute ischemic stroke is effective and includes different technical approaches. Operators use direct aspiration, a stent retriever, or a combination of both. Direct aspiration can be performed with various catheters of different sizes depending on the diameter of the occluded vessel.

PURPOSE

We studied the relationship between the catheter diameter in regards to the occluded vessel diameter and the rate of successful recanalization.

MATERIALS AND METHODS

We conducted a retrospective, monocentric study on a series of consecutive patients treated with mechanical thrombectomy. For each procedure, we extracted each attempt that used direct aspiration and rated the attempt as successful or unsuccessful. We also measured the occluded artery diameter and calculated the ratio between the occluded artery and the aspiration catheter diameters. We tested the association between the diameter ratio and the recanalization status. We also performed inter-rater agreement for the arterial diameter measurement between three interventional neuroradiologists.

RESULTS

We included 119 patients with 201 attempts of direct aspiration. A higher diameter ratio was associated with a higher recanalization rate. The analysis in terciles showed that the odds of success were 4.80 higher when the ratio was >0.71 vs <0.54 (p < 0.01). Inter-rater agreement showed near-perfect intraclass correlation with 0.93 (0.91-0.94) consistency and 0.92 (0.90-0.94) absolute agreement.

CONCLUSIONS

We demonstrated an association between higher recanalization and a diameter of ratio >0.71 between the aspiration catheter and the occluded artery. These results could guide intraoperative decisions regarding the appropriate selection of aspiration catheters during mechanical thrombectomy increasing the rate of successful recanalisation. A larger study could provide additional data to further specify the optimal ratio.

Mechanical thrombectomy in minor stroke due to isolated M2 occlusion: a multicenter retrospective matched analysis

BACKGROUND

The purpose of this study was to evaluate the effectiveness of mechanical thrombectomy (MT) in patients with isolated M2 occlusion and minor symptoms and identify possible baseline predictors of clinical outcome.

METHODS

The databases of 16 high-volume stroke centers were retrospectively screened for consecutive patients with isolated M2 occlusion and a baseline National Institutes of Health Stroke Scale (NIHSS) score ≤5 who received either early MT (eMT) or best medical management (BMM) with the possibility of rescue MT (rMT) on early neurological worsening. Because our patients were not randomized, we used propensity score matching (PSM) to estimate the treatment effect of eMT compared with the BMM/rMT. The primary clinical outcome measure was a 90-day modified Rankin Scale score of 0-1.

RESULTS

388 patients were initially selected and, after PSM, 100 pairs of patients receiving eMT or BMM/rMT were available for analysis. We found no significant differences in clinical outcome and in safety measures between patients receiving eMT or BMM/rMT. Similar results were also observed after comparison between eMT and rMT. Concerning baseline predicting factors of outcome, the involvement of the M2 inferior branch was associated with a favorable outcome.

CONCLUSION

Our multicenter retrospective analysis has shown no benefit of eMT in minor stroke patients with isolated M2 occlusion over a more conservative therapeutic approach. Although our results must be viewed with caution, in these patients it appears reasonable to consider BMM as the first option and rMT in the presence of early neurological deterioration.

A review of acute ischemic stroke caused by distal, medium vessel occlusions

Acute ischemic stroke (AIS) due to distal, medium vessel occlusion (DMVO) is increasingly recognized as the next frontier for mechanical thrombectomy. Distal, medium vessel occlusions are typically defined as an occlusion in the following arteries: anterior cerebral artery, M2-M4 segments of the middle cerebral artery, posterior cerebral artery, posterior inferior cerebellar artery, anterior inferior cerebellar artery, and superior cerebellar artery. It is estimated that 25-40% of all AIS is due to DMVO. Because of the large burden of DMVO, the frequency of literature published regarding these occlusions has greatly increased in recent years. Furthermore, treatment modalities have been created specifically for DMVOs. Due to the rapidly evolving literature on this topic, remaining up to date on DMVO definitions, anatomy, management, imaging, and clinical course is difficult. In this review article, we synthesized existing literature regarding the aforementioned topics and discussed future directions.

Anatomical distribution and clinical significance of middle cerebral artery M2 segment vessel occlusions and its cortical branches in acute ischaemic stroke patients

Background

Characterisation of anatomical distribution and the clinical impact of middle cerebral artery M2 (MCA-M2) segment occlusion and its subsequent cortical branches (CBs) in acute ischaemic stroke patients (AIS).

Methods

Retrospective, monocentric study analysing radiological and clinical data of AIS patients with MCA-M2 segment occlusion with regard to the anatomic distribution of MCA-M2 occlusion and its subsequent CB.

Results

A total of 203 patients (median age 77 (IQR 66-83) years, 112 women) were included. There was an equal distribution of right-sided versus left-sided MCA-M2 vessel occlusions (right: n=97; left: n=106), as well as with a median number of affected MCA-M2 CBs of 4 (IQR, 3-6) and a median National Institute of Health Stroke Scale score (NIHSS) on admission of 9 (3-15). For both hemispheres, CBs of the inferior trunks were significantly more affected than the superior trunks. Endovascular treatment (EVT, n=94) was associated with a significant better outcome compared with patients with medical management alone (p=0.027).

Conclusion

In acute MCA-M2 segment occlusions, inferior trunks are significantly more affected compared with the superior trunks. The subsequent CBs of the paracentral region of both hemispheres are more commonly involved. In eloquent vascular territories, EVT was more often performed.

Cost-effectiveness of endovascular thrombectomy in patients with acute stroke and M2 occlusion

BACKGROUND

The cost-effectiveness of endovascular thrombectomy (EVT) in patients with acute ischemic stroke due to M2 branch occlusion remains uncertain.

OBJECTIVE

To evaluate the cost-effectiveness of EVT compared with medical management in patients with acute stroke presenting with M2 occlusion using a decision-analytic model.

METHODS

A decision-analytic study was performed with Markov modeling to estimate the lifetime quality-adjusted life years and associated costs of EVT-treated patients compared with no-EVT/medical management. The study was performed over a lifetime horizon with a societal perspective in the Unites States setting. Base case, one-way, two-way, and probabilistic sensitivity analyses were performed.

RESULTS

EVT was the long-term cost-effective strategy in 93.37% of the iterations in the probabilistic sensitivity analysis, and resulted in difference in health benefit of 1.66 QALYs in the 65-year-old age groups, equivalent to 606 days in perfect health. Varying the outcomes after both strategies shows that EVT was more cost-effective when the probability of good outcome after EVT was only 4-6% higher relative to medical management in clinically likely scenarios. EVT remained cost-effective even when its cost exceeded US$200 000 (threshold was US$209 111). EVT was even more cost-effective for 55-year-olds than for 65-year-old patients.

CONCLUSION

Our study suggests that EVT is cost-effective for treatment of acute M2 branch occlusions. Faster and improved reperfusion techniques would increase the relative cost-effectiveness of EVT even further in these patients.

Treatment and Outcome in Stroke Patients With Acute M2 Occlusion and Minor Neurological Deficits

BACKGROUND AND PURPOSE

Treatment in stroke patients with M2 segment occlusion of the middle cerebral artery presenting with mild neurological deficits is a matter of debate. The main purpose was to compare the outcome in patients with a minor stroke and a M2 occlusion.

METHODS

Consecutive intravenous thrombolysis (IVT) eligible patients admitted to the Bernese stroke center between January 2005 and January 2020 with acute occlusion of the M2 segment and National Institutes of Health Stroke Scale score ≤5 were included. Outcome was compared between IVT only versus endovascular therapy (EVT) including intra-arterial thrombolysis and mechanical thrombectomy (MT; ±IVT) and between IVT only versus MT only.

RESULTS

Among 169 patients (38.5% women, median age 70.2 years), 84 (49.7%) received IVT only and 85 (50.3%) EVT (±IVT), the latter including 39 (45.9%) treated with MT only. Groups were similar in sex, age, vascular risk factors, event cause, or preevent independency. Compared with IVT only, there was no difference in favorable outcome (modified Rankin Scale score, 0-2) for EVT (adjusted odds ratio, 0.96; adjusted P=0.935) or for MT only (adjusted odds ratio, 1.12; adjusted P=0.547) groups. Considering only patients treated after 2015, there was a significantly better 3-month modified Rankin Scale shift (adjusted P=0.032) in the EVT compared with the IVT only group.

CONCLUSIONS

Our study demonstrates similar effectiveness of IVT only versus EVT (±IVT), and of IVT only versus MT only in patients with peripheral middle cerebral artery occlusions and minor neurological deficits and indicates a possible benefit of EVT considering only patients treated after 2015. There is an unmet need for randomized controlled trials in this stroke field, including imaging parameters, and more sophisticated evaluation of National Institutes of Health Stroke Scale score subitems, neurocognition, and quality of life neglected by the standard outcome scales such as modified Rankin Scale and National Institutes of Health Stroke Scale score.

Neuroanatomy of the middle cerebral artery: implications for thrombectomy

Our perspective on anatomy frequently depends on how this anatomy is utilized in clinical practice, and by which methods knowledge is acquired. The thrombectomy revolution, of which the middle cerebral artery (MCA) is the most common target, is an example of a clinical paradigm shift with a unique perspective on cerebrovascular anatomy. This article reviews important features of MCA anatomy in the context of thrombectomy. Recognizing that variation, frequently explained by evolutionary concepts, is the rule when it comes to branching pattern, vessel morphology, territory, or collateral potential is key to successful thrombectomy strategy.