Evaluation of mechanical thrombectomy in acute ischemic stroke related to a distal arterial occlusion: A randomized controlled trial

Advances in the Critical Care of Ischemic Brain Infarction

Acute care for ischemic stroke has dramatically evolved over the last years. Cerebral reperfusion is possible up to 24 h after symptoms onset. Advanced brain imaging allows identifying salvageable ischemic brain tissue, and the development of newer endovascular devices permits access to distal vessels. Monitoring for neurologic deterioration, diagnosis of stroke etiology, and secondary prevention treatments are important after initial treatment. This article reviews the recent advancements in the critical care of acute ischemic stroke.

[Endovascular thrombectomy of medium vessel occlusions]

BACKGROUND

Acute ischemic stroke is a leading cause of disability and dependency in daily life. While endovascular therapy has become the standard treatment for large vessel occlusions, its benefit for medium vessel occlusions has not yet been clearly established.

OBJECTIVE

This article provides an overview of the current evidence, epidemiology, and clinical challenges of thrombectomy in distal medium vessel occlusions (DMVOs).

Mechanical thrombectomy failure in anterior and posterior circulation stroke: current results from a high-volume comprehensive center

BACKGROUND

Mechanical thrombectomy (MT) is an established therapy for acute ischemic stroke (AIS), but recanalization is not always achieved. Common reasons are inadequate removal at the thrombus site and difficulties with the access route. In order to identify risk factors for MT failure we conducted a retrospective study on a high-volume comprehensive stroke center.

METHODS

Evaluation of 552 thrombectomies (2019-23; anterior and posterior circulation, direct aspiration +/- stent retriever [SR]). MT failures (= modified Thrombolysis in Cerebral Infarction score 0 or 1) were analyzed for age, sex, pre- and post-MT modified Rankin Scale, bridging intravenous thrombolysis (IVT), occlusion site (anterior / posterior circulation, proximal / distal), the Kaesmacher classification and time trend results.

RESULTS

MT failure occurred in 56 patients (10.1%; median age 76; 53.6% female). Nineteen (33.9%) patients received IVT (p = 0.326). Logistic regression analysis did not show a significant association of age, sex or occlusion site with MT failure (p = 0.165, p = 0.738, p = 0.838). Distal MT generally demonstrated lower success rates (p < 0.01). According to the Kaesmacher classification SR failure was the most frequent cause of MT failure (category 2B: 48%, p < 0.001). Time trend analysis suggests improving recanalization rates in the further course (4 times in year-on-year comparison; p < 0.01).

CONCLUSION

MT failure occurs in AIS treatment, even in high-volume centers and occurs more frequently in distal occlusions. Improvements in device technology, particularly SR, and ongoing refinements in access route selection offer the prospect of better outcomes in the future.

Trial selection criteria should not be used for clinical decisions and recommendations: the thrombectomy trials example

BACKGROUND

Despite multiple calls for more inclusive studies, most clinical trial eligibility criteria remain too restrictive. Thrombectomy trials have been no exception.

METHODS

We review the landmark trials that have shown the benefits of thrombectomy, their eligibility criteria, and consequences on clinical practice. We discuss the rationale behind various reasons for exclusions. We also examine the logical problem involved in using eligibility criteria as indications for treatment.

RESULTS

Most thrombectomy trials have been too restrictive. This has been shown by a plethora of follow-up studies that have refuted most of the previously recommended trial eligibility restrictions. Meanwhile, the effect of clinical recommendations based on restrictive eligibility criteria is that treatment has been denied to the majority of patients who could have benefitted. Trial eligibility criteria cannot be used to make clinical decisions or recommendations unless, like any other medical diagnosis, they have been shown capable of reliably differentiating patients into those that will, and those that will not benefit from treatment. This goal can only be achieved with all-inclusive pragmatic trials.

CONCLUSION

Restrictive eligibility criteria render clinical trials incapable of guiding medical decisions or recommendations.

Common design and data elements reported in active mechanical thrombectomy trials focusing on distal medium vessel occlusions and minor strokes: a systematic review

BACKGROUND

Distal medium vessel occlusions (DMVOs) and minor strokes represent emerging frontiers in mechanical thrombectomy (MT). Although several randomized clinical trials (RCTs) are underway, the design characteristics of these trials and the specific questions they aim to address have not been extensively explored. This current study sought to investigate the design and data elements reported in active prospective DMVO and minor stroke studies.

METHODS

The ClinicalTrials.gov database was searched for ongoing prospective studies assessing the role of MT in patients with DMVOs or minor strokes. The Nested Knowledge AutoLit platform was utilized to categorize reported outcomes and inclusion/exclusion criteria. Frequencies of reported data elements were extracted from study protocols.

RESULTS

A total of 10 (8 DMVO and 2 minor stroke) studies enrolling 3520 patients were included. All DMVO studies employ different criteria regarding target occlusion locations. Five DMVO studies use stent retrievers as the first-line thrombectomy technique (62.5%, 5/8), while three studies allow any MT techniques, generally at the operator's discretion. Four DMVO studies permit intravenous thrombolysis (IVT) utilization in both intervention and control arms (50%, 4/8). The DISTALS trial excludes patients receiving IVT, while the DUSK trial and Tigertriever registry only enroll patients who are ineligible for IVT or for whom IVT failed to achieve reperfusion. DMVO studies exhibit notable heterogeneity in symptom onset duration thresholds for inclusion (<6 hours: 2 studies; <12 hours: 2 studies; <24 hours: 3 studies). Minor stroke trials employ similar inclusion criteria and outcome measures except for symptom duration thresholds for inclusion (8 hours for ENDOLOW and 23 hours for MOSTE).

CONCLUSIONS

There is considerable heterogeneity among active DMVO trials regarding potential target DMVO locations and time thresholds for inclusion based on the last known well time. Furthermore, our review indicates that the utility of aspiration thrombectomy in DMVOs and the advantages of MT without IVT over IVT alone will remain largely unexplored even after completion of active DMVO trials.