Authors
8 of 15Shahram MajidiAmol M. MehtaSami Al KasabKaustubh S. LimayeAdam Andrew DmytriwAdam de HavenonFarhan SiddiqRobin Novakovic
Topics
Acute Ischemic Stroke ManagementVenous Thromboembolism Diagnosis and ManagementIntracerebral and Subarachnoid Hemorrhage ResearchStroke: Vascular and Interventional Neurology is available at www.ahajournals.org/journal/svinShahram Majidi , MD; Amol Mehta , MD; Sami Al-Kasab , MD; Kaustubh Limaye , MD; Adam A. Dmytriw , MD, MPH, MSc; Adam de Havenon , MD, MS; Farhan Siddiq , MD; Robin Novakovic , MD; Alexandra L Czap , MD; Ossama Mansour , MD, PhD; Cynthia L Kenmuir , MD, PhD; Ameer E. Hassan , DO; David Liebeskind , MD; Thanh N. Nguyen , MD; Waldo R. Guerrero , MDCorrespondence to: Shahram Majidi, MD, Department of Neurosurgery, Department of Neurology, and Department of Diagnostic, Molecular and Interventional Radiology, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, New York, NY 10029. Email Shahram.Majidi@mountsinai.org This manuscript was sent to Natalia Pérez de la Ossa Herrero, Guest Editor, for review by expert referees, editorial decision, and final disposition. This article presents practice guideline recommendations developed by the Society of Vascular and Interventional Neurology (SVIN) Guidelines and Practice Standards Committee. © 2026 The Authors. Stroke: Vascular and Interventional Neurology is published on behalf of the American Heart Association, Inc. and the Society for Vascular and Interventional Neurology by Wolters Kluwer Health, Inc. This is an open access article distributed under the terms of the Creative Commons Attribution Non Commercial License 4.0, which permits use, distribution, and reproduction in any medium, provided that the original work is properly cited, the use is noncommercial.BACKGROUND: The authors present an overview of the current evidence and management recommendations for evaluation and treatment of adults with acute ischemic stroke from distal- and medium-vessel occlusion (DMVO) for endovascular thrombectomy (EVT). The intended audiences are prehospital care providers, physicians, and allied health professionals. METHODS: The Society of Vascular and Interventional Neurology Guidelines and Practice Standards committee formed a writing group to conduct a structured literature review on EVT for DMVO-related acute ischemic stroke and to draft practice recommendations in accordance with the Society of Vascular and Interventional Neurology Guidelines and Practice Algorithm. A structured literature search was conducted across PubMed, MEDLINE, and the Cochrane Library from January 2015 through February 2026, supplemented by manual review of reference lists from key studies and conferences. Recommendations were developed with consensus from an expert panel and the Guidelines and Practice Standards committee, with final approval by the Society of Vascular and Interventional Neurology Board of Directors. RESULTS: Data from all randomized controlled trials, prior meta-analyses, and subgroup analyses were extracted to evaluate the latest evidence on the safety and efficacy of EVT in patients presenting with DMVO acute ischemic stroke. The guideline outlines practical considerations for patient selection, procedural technique, and systems of care. CONCLUSIONS: These guidelines provide focused practical recommendations based on recent evidence regarding patient selection and decision-making for EVT in patients presenting with acute DMVO. Routine EVT for DMVO is not supported by current evidence; however, performing EVT in patients with disabling acute dominant M2 occlusion remains reasonable. GRAPHIC ABSTRACT: A graphic abstract is available for this article.Key Words: guideline ◼ ischemic stroke ◼ neurology ◼ stents ◼ thrombectomy istal- and medium-vessel occlusions (DMVO) involve distal intracranial arteries and account for roughly 25% to 40% of acute ischemic strokes. 1 Although there is some heterogeneity in the definition of DMVO, these typically include occlusions of the M2-M3 segment of the middle cerebral artery (MCA), the A1-A3 segments of the anterior cerebral artery (ACA), and the P1-P3 seg ments of the posterior cerebral artery (PCA). Although the benefit of endovascular thrombectomy (EVT) for proximal large vessel occlusions (LVOs) has been well established, 2–6 its benefit in DMVO remains uncertain. The 2019 American Heart Association/American Stroke Association guidelines acknowledge that EVT for DMVO “may be reasonable” (class IIb) for select patients pre senting within 6 hours of symptom onset. 7 Recently, several randomized controlled trials (RCTs), including the ESCAPE-MeVO (Endovascular Treatment to Improve Outcomes for Medium Vessel Occlusions), 8 DISTAL (Endovascular Therapy Plus Best Medical Treatment [BMT] Versus BMT Alone for Medium Ves sel Occlusion Stroke), 9 and DISCOUNT (Evaluation of Mechanical Thrombectomy in Acute Ischemic Stroke Related to a Distal Arterial Occlusion) trials 10 did not demonstrate a benefit of EVT over best medical man agement for patients with DMVO acute ischemic stroke. However, these trials were subject to selection bias and other methodological limitations, and there remains a suggestion that certain subgroups of patients may still benefit from EVT. 11 Importantly, in February 2026, the ORIENTAL-MeVO (Endovascular Treatment in Acute Intracranial Distal Medium Vessel Occlusion Stroke) 12 and DISTALS (Distal Ischemic Stroke Treatment With Adjustable Low-Profile Stentriever) trials were presented at the International Stroke conference. At this time, pub lication of these trials is still pending. ORIENTAL-MeVO, which enrolled 564 patients with baseline National Insti tutes of Health Stroke Scale (NIHSS) scores ≥6 and less thrombolysis usage, demonstrated that EVT significantly improved functional independence (modified Rankin Scale [mRS] score 0–2) compared with BMM. Benefit was driven by patients with NIHSS score ≥8. 12 The DIS TALS 13 trial demonstrated that thrombectomy with the Tigertriever 13 achieved 3-fold greater successful reper fusion without symptomatic intracranial hemorrhage (sICH) compared with medical management (86.3% ver sus 27.7%, P<0.001), with zero sICH in the per-protocol treatment arm. 14 In addition, the recently published 2026 2019 American Heart Association/American Stroke Association guidelines for the early management of acute ischemic stroke gave a class III recommendation suggesting no benefit for the treatment of proximal/ nondominant or codominant M2 segment of the MCA, distal MCA, ACA, or PCA. Some experts may find this too restrictive given the evolving evidence landscape, and given that the American Heart Association guidelines were published before the presentation of ORIENTAL MEVO and DISTALS. 15 The following recommendations—structured by vas cular territory (M2, M3/M4, A2-A4, P1-P4)—provide evidence-based guidance on the use of EVT for DMVO. Each recommendation is assigned to a Class of Recom mendation and Level of Evidence (LOE) according to Society of Vascular and Interventional Neurology–Guide lines and Practice Standards criteria 16 and is supported by the latest trial evidence in addition to the available observational data (Figure 1).The M2 segment of the MCA (insular segment) supplies a substantial portion of the cerebral hemisphere, and consequently, M2 occlusions can cause disabling defi cits, especially when the occlusion involves a dominant branch (typically defined as supplying >50% of the MCA territory). The M2 segment is heterogeneously classified and has great anatomic variability. However, it is classi cally defined as originating at the M1 bifurcation after the division into superior and inferior branches, typically as vertically directed insular MCA branches. Historically, many stroke centers have pursued EVT for M2 occlu sions, 17 and strong observational evidence, as well as post hoc randomized data, have suggested that EVT can be beneficial in these patients. 18,19 Proximal and dominant M2 occlusions remain underrepresented—not only in recent DMVO trials but also in earlier randomized studies, as reflected in the HERMES (Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials) meta-analysis. In the HERMES pooled analysis of 7 randomized trials, only 11% of patients (130 patients) had M2 occlusions, with 116 (89%) being proximal and 73 (56%) being domi nant M2 occlusions. EVT was highly effective in this sub population (90-day mRS score, 0–2; adjusted odds ratio, 2.68 [95% CI, 1.13–6.37]), with dominant M2 occlusions benefitting substantially (adjusted odds ratio, 4.08 [95% CI, 1.08–15.48]). A pooled analysis of the EXTEND-IAACA anterior cerebral artery DMVO distal- and medium-vessel occlusion EVT endovascular thrombectomy LVO large vessel occlusion MCA middle cerebral artery mRS modified Rankin Scale NIHSS National Institutes of Health Stroke Scale PCA posterior cerebral artery RCT randomized controlled trial tPA tissue-type plasminogen activator (Extending the Time for Thrombolysis in Emergency Neurological Deficits — Intra-Arterial), EXTEND-IA-TNK (Tenecteplase Versus Alteplase Before Endovascular Therapy for Ischemic Stroke), INSPIRA (International Stroke Perfusion Imaging Registry), and SELECT (Opti mizing Patient’s Selection for Endovascular Treatment in Acute Ischemic Stroke) trials focused on EVT for iso lated M2 occlusions, using NIHSS score and mismatch profile to assess stroke severity, demonstrating improved functional independence with EVT, particularly among patients with favorable perfusion mismatch and higher baseline NIHSS scores. 20 However, a secondary analysis of the CLEAR study (CT for Late Endovascular Reperfu sion) showed that in patients with M2 occlusion present ing in the 6 to 24 hour window, EVT conferred no benefit compared with medical management. 17 The MR CLEAN registry also demonstrated that EVT performed in M1 and M2 had similar rates of good outcome and a similar complication profile. 21 In 2025, the ESCAPE-MeVO trial (n=530), the DIS TAL trial (n=543), as well as the interim results from the DISCOUNT trial (n=163) provided Level I evidence on M2-M4, A1-A3, and P1-P3 occlusions. The ESCAPE MeVO trial enrolled patients with proximal M2 occlusion, whereas the DISTAL trial only included patients with codominant or nondominant M2 occlusions. These tri als found there was no overall improvement in 90-day functional outcomes with EVT compared with best medi cal management. 8–10 In ESCAPE-MeVO, the primary out come of 90-day mRS score of 0 to 1 was 41.6% with EVT versus 43.1% with medical therapy (adjusted rate ratio, 0.95 [95% CI, 0.79–1.15]). Similarly, the rate of mRS score of 0 to 2 was 54.1% (EVT) versus 58.8% (medical management). Notably, there was higher mor tality in the EVT group of the ESCAPE-MeVO trial (13.3% versus 8.4%; adjusted hazard ratio 1.82 [95% CI, 1.06–3.12]). The DISTAL trial likewise reported no reduction in disability with EVT (excellent outcome odds ratio, 0.88 [95% CI, 0.61–1.25]), and 90-day mortality was similar between groups (15.5% versus 14%). In the interim analysis of the French DISCOUNT trial, EVT like wise failed to improve functional outcomes (mRS score of 0–2: 60% [EVT] versus 77% [medical management]). In February 2026, the ORIENTAL-MeVO trial was presented at the International Stroke Conference with results that significantly shift the evidence landscape. 12 This trial randomized 564 patients with MeVO and NIHSS score ≥6 to EVT plus medical management ver sus medical management alone. The study demonstrated that EVT significantly improved functional independence at 90 days (mRS score of 0–2: 58.6% versus 46.6%, P=0.009) and that the benefit was particularly driven by patients with moderate-to-severe deficits (NIHSS score ≥8). Crucially, the included M2’s were codominant or Figure 1. Society of Vascular Interventional Neurology Guidelines and Practice Standards (GAPS) algorithm for applying the LOE of COR to intervention, approach, and treatment. LD indicates limited data; NR, nonrandomized; R, randomized; and RCT, randomized controlled trial. Adapted from Otto et al 70 with permission. Copyright ©2021, the American College of Cardiology Foundation and the American Heart Association, Inc.nondominant. In total, 122 of the patients had M2 occlu sions, and the treatment effect for these patients was the highest in the reported subgroups (adjusted rate ratio, 1.43 [95% CI, 1.12–1.82]). These findings are critical and must be taken into consideration when making EVT decisions for DMVO. The DISTALS trial evaluated EVT with the Tigertriever 13, an adjustable stent retriever purpose-built for distal vessel occlusions. The DISTALS trial demonstrated a 3-fold greater successful reperfusion without sICH when compared with the medical management arm (86.3% versus 27.7%, P<0.001), with notably zero sICH in the per-protocol treatment arm. With regards to M2 occlu sions, the trial only enrolled M2 codominant and non dominant occlusions (n=47). Importantly, the neutral 2025 DMVO trials had strict inclusion criteria, which potentially affected the spec trum of M2 occlusions enrolled. Both ESCAPE-MeVO and DISTAL distinguished dominant versus nondomi nant M2 branches and predominantly enrolled non dominant M2 occlusions, possibly excluding the most extensive M2 infarcts. 11 This is also supported by the low median NIHSS scores (eg, median NIHSS score of 6 in DISTAL). Similarly, the interim DISCOUNT cohort had relatively mild strokes (median NIHSS score of 8) and did not specifically include or characterize domi nant M2 occlusions. This raises concern that patients with more severe M2 occlusion strokes (who often have NIHSS scores >10 and large territory at risk) were underrepresented—indeed, such patients may have been treated outside of the trials due to lack of equi poise. The trial findings, therefore, should be interpreted with caution for proximal or dominant M2 occlusions that cause substantial deficits. Observational series and prior meta-analyses indicate that these large M2 occlu sions can benefit from EVT, and many practitioners con tinue to offer EVT for these patients. 19,21–25 However, it should be noted that large observational cohorts that combine M2 and M3 occlusions have shown neutral results. 26 Of note, in the more recent ORIENTAL-MeVO trial and the DISTALS trial, many of these shortcom ings were accounted for. There was explicit exclusion of codominant and nondominant M2 occlusions in both trials, and the inclusion criteria in DISTALS required an NIHSS score of ≥6, with the median NIHSS score of 10 in the trial. The 2025 DMVO RCTs inform us that many M2 patients will do well with medical therapy—for instance, in ESCAPE-MeVO nearly half of patients in both EVT and medical arms achieved mRS score of 0 to 2. 8 Fur thermore, the risk of sICH was not negligible: ESCAPE MeVO reported sICH in 5.4% of EVT patients versus 2.2% with medical therapy, and DISCOUNT showed sICH 12% versus 6%. 10 These findings highlight the need for careful selection- focusing on patients with sub stantial deficits, large at-risk territory, limited infarct core, favorable collaterals, and rapid treatment eligibility. 27 Sub group analyses suggest time may be a factor: ESCAPE MeVO found a trend toward better outcomes with EVT in patients treated earlier (<4.5 hours). 8 This was also seen in the ORIENTAL-MeVO subgroup analyses, with both ≤ 4.5 hours as well as 4.5 to 8 hours demonstrating a positive effect for M2 occlusions. Thus, as with LVO, rapid treatment is important—delays in reperfusion can reduce the benefit, especially because DMVOs may have different collateral circulation profiles than more proximal occlusions. Altogether, for M2 occlusions, although EVT for all M2 strokes is not supported by RCTs, a nuanced, case-by-case approach is warranted, specifically when dealing with dominant and codominant M2 occlusion as well as those with a higher NIHSS score. 28,29 The very concept of dominance remains one of considerable debate, as the dominant hemisphere may be more rel evant than the dominant branch or division. In addition, because the NIHSS score may underestimate functional impact in DMVO, many centers apply a disabling deficit framework (eg, aphasia, hemianopia, prominent motor deficits) and consider the risk of early neurological dete rioration when selecting patients for EVT, even when the baseline NIHSS score is low. 30,31Large trials comparing first-line aspiration and stent retriever EVT for LVO have demonstrated comparable efficacy. The ASTER (Contact Aspiration Versus Stent Retriever for Successful Revascularization) and COM PASS (A Comparison of Direct Aspiration Versus Stent Retriever as a First Approach) trials found no significant difference in final reperfusion or functional indepen dence at 90 days between contact aspiration and stent retriever approaches. 32–34 In a post hoc ASTER analysis focusing on isolated M2 occlusions (79 patients), aspira tion and stent retrievers achieved similar revasculariza tion rates (modified Thrombolysis in Cerebral Infarction ≥2b ≈90% versus 84%, P=0.36) and 90-day good out comes (≈54% versus 50%). 32 This was also supported by nonrandomized studies, which demonstrate compa rable efficacy, including a large multicenter retrospective study directly comparing these 2 techniques. 35–39 There is some suggestion, however, that the use of stent retriev ers in DMVOs may be associated with a higher rate of hemorrhagic complications, likely owing to these being more tortuous and fragile vessels; technical nuances such as partial deployment may mitigate this risk, though their clinical impact remains uncertain. 25,40–44 However, in patients with PCA occlusion, the PLATO study (Poste rior Cerebral Artery Occlusion) showed higher rates of first pass effect with stent retriever compared with con tact aspiration or combined technique, and with better outcomes. 45A principal advantage of direct aspiration is the ability to remove the thrombus by engaging it at the proximal occlusion face without the need to traverse the clot. In contrast, deployment of a stent retriever requires crossing the occlusion with a microguidewire and microcatheter, which in small M2 or distal branches may increase the risk of endothelial injury or perfora tion. The relatively higher incidence of vessel injury, subarachnoid hemorrhage, and vasospasm observed with stent retrievers compared with aspiration may not substantially influence clinical outcomes in LVO EVT, given the greater absolute benefit derived from recanalization in this population. However, in DMVO, where the efficacy gap between best medical manage ment and EVT is narrower, even a modest increase in procedure-related complications may negatively influ ence the clinical outcome and offset the treatment effect. There is some suggestion that an aspiration-first approach may represent a favorable initial strategy for DMVO EVT, especially in the case of M2 occlusions, 40,46 although the DISTAL trial did not show any difference in outcomes across different techniques, and large prior observational cohorts have not demonstrated differ ences between approaches. 39,47 It should be noted, however, that the Tigertriever 13 device used in the DISTALS trial is a low-profile, adjust able stent retriever that is purpose-built for DMVO. The encouraging preliminary trial results from DISTALS fur ther support the notion that devices designed specifically for distal vessels may be associated with a much more favorable risk/benefit profile, and thus may change the calculus in making DMVO EVT decision-making.Vessel perforation during EVT is a serious complication that carries the risk of catastrophic intracranial hemor rhage and poor clinical outcomes. A multicenter study analyzed data from 1373 patients undergoing EVT for DMVO and found an overall incidence of vessel perfo ration of 4.8%. Perforation rates were notably higher in DVO (M3: 8.9%, A2: 8.3%) compared with more proxi mal M2 occlusions (4.3%). 48 These data highlight the increased technical challenge and complication risk when treating the most distal vessel occlusions. Predic tors of perforation include smaller vessel diameter, dis tal location, tortuosity of vessel anatomy, and prolonged procedure time. Mitigation strategies include careful guidewire and microcatheter selection to minimize ves sel wall trauma, gentle aspiration or retriever advance ment, awareness of normal anatomic variants, and rapid recognition and management of perforation (includ ing reversal of anticoagulation and careful hemosta sis with consideration of angiographic monitoring and vasopressor support). Operators should maintain high clinical suspicion for perforation-related complications during and immediately after DMVO thrombectomy procedures.• EVT is reasonable for patients with disabling stroke due to proximal and/or dominant M2 occlusions, par ticularly when associated with moderate-to-severe deficits and imaging evidence of salvageable brain tis sue (class IIa; LOE B-nonrandomized).• EVT may be considered in distal, codominant, or non dominant M2 occlusions who present with disabling deficits and an NIHSS score ≥6 (class IIb; LOE B-randomized).• Routine EVT is not recommended for patients with distal or nondominant M2 occlusions presenting with low stroke severity and nondisabling symptoms (class III: no benefit; LOE A).Rationale Subgroup analyses from HERMES and multiple obser vational cohorts demonstrate the substantial benefit of EVT in proximal and dominant M2 occlusions. These occlusions frequently involve large cortical territories and may clinically resemble proximal LVO. Importantly, recent 2025 DMVO RCTs predominantly enrolled nondominant and lower-NIHSS M2 strokes, limiting the generalizabil ity of their neutral findings to higher-severity proximal or dominant M2 occlusions. Practical Considerations EVT should be considered for proximal and/or dominant M2 occlusions with significant deficits, large at-risk ter ritory, or dominant-branch involvement. Imaging should confirm a limited core infarct and a favorable collateral status. Rapid treatment remains essential. Rationale Whereas ESCAPE-MeVO, DISTAL, and DISCOUNT did not demonstrate the overall benefit of routine EVT in nondominant M2 occlusions, the ORIENTAL-MeVO trial demonstrated improved functional independence in patients with an NIHSS score ≥6, with the strongest treatment effect observed in the M2 subgroup. These findings suggest that stroke severity and clinical disabil ity may be important determinants of benefit. Practical Considerations Patient selection should incorporate NIHSS score sever ity, eloquence of the deficit, infarct core size, perfusion mismatch (if available), and procedural risk. EVT in this category should be individualized rather than routine. Rationale Across ESCAPE-MeVO, DISTAL, and DISCOUNT, patients with mild, nondominant M2 occlusions did not experience improved functional outcomes with EVT and demonstrated higher rates of symptomatic intracranial hemorrhage. These data do not support indiscriminate treatment of low-severity M2 occlusions. In DISTALS, these patients were not found to have an increased rate of sICH.Practical Considerations Best medical management, including IV thrombolysis when eligible, is appropriate in this population. EVT may be considered only in rare cases with clearly disabling symptoms despite a low NIHSS score or imaging sug gesting substantial threatened territory.M3/M4 SEGMENTS OCCLUSIONSM3 and M4 refer to the more distal MCA branches—M3 (opercular segment) courses over the cortical surface after the M2 segments exit the Sylvian fissure, and M4 are the small cortical penetrating branches on the brain surface. Occlusions in M3/M4 branches typically pro duce smaller, more focal strokes (eg, restricted to one gyrus or cortical region). Often these strokes result in mild to moderate deficits (such as isolated hand weak ness, partial sensory loss, or a quadrant of visual field deficit), and some can recover well with medical ther apy alone. However, certain M3 occlusions can still be disabling (eg, an M3 occlusion in the precentral branch causing dense hand/arm weakness, or in a temporo occipital branch causing aphasia). The clinical presenta tion, therefore, varies widely depending on which cortical territory is affected.Evidence From Trials Overall, 27% of patients in the DISTAL trial had M3/M4 segment occlusions. As previously noted, this trial found no significant difference in 90-day disability between the EVT group and the medical management group. The subgroup analysis for M3/M4 occlusions (adjusted odds ratio, 0.77 [95% CI, 0.44–1.37]) also did not demonstrate a functional benefit for EVT. ESCAPE-MeVO included 216 (41%) patients with M3 occlusions, with the sub group analysis demonstrating no benefit (adjusted odds ratio, 1.01 [95% CI, 0.77–1.31]). The rate of sICH was also found to be higher in the EVT arm (5.9% versus 2.6%). Overall, 76% of patients in the DISCOUNT trial had M3 occlusions. Interim results suggested a poten tial trend toward worse outcomes with EVT, as 90 days with an mRS score of 0 to 2 being 60% in the EVT and 77% in the medical management arm, leading to trial stoppage. There was also a higher overall rate of ICH in DISCOUNT (44% versus 29%). Although these results are not specifically reflective of M3/M4 occlusion out comes, they suggest that indiscriminately treating distal MCA occlusions may not help and could potentially harm. Although the ORIENTAL-MeVO trial was a positive one, in subgroup analyses, M3 occlusions (n=54) were not found to have a significant benefit with regard to func tional outcomes. There are a few additional considerations when inter preting the findings of these trials. First, it is worth not ing that the RCTs may not have identified a subgroup of M3/M4 patients who benefit, but this does not mean none exist. These trials included patients with relatively low NIHSS scores, which is not uncommon for M3/M4 occlusions; however, patients who presented with more severe deficits may have been treated outside the trial, introducing selection bias. Furthermore, device selection could play an important role, particularly in smaller, more delicate vessels. It remains possible that with newer devices designed for distal EVT, rates of sICH may decrease, and recanalization outcomes might improve. The use of stent retrievers in these small tortuous ves sels may have contributed to an increased rate of ICH. This has been shown in prior studies with higher rates of sICH in M3/M4 vessels. 49,50 However, it should be noted that none of the 28 M3 patients in the positive DISTALS trial were found to have sICH. In addition, the rates of intravenous tPA (tissue-type plasminogen activator) were high in these randomized trials (60%–70%). The strategy for EVT decision-making for M3/M4 occlusions should be on a case-by-case basis. The strat egy should be based on the level of disability; generally, an NIHSS score threshold of ≥5 is reasonable for dis tal occlusions (aligning with ESCAPE-MeVO’s criteria of NIHSS score >5 or 3–5 with disabling deficit). The deficit should be eloquent—for example, causing sig nificant functional impairment (aphasia, hemianopia, hemiparesis) and more than a mild, nondisabling deficit. This, in conjunction with infarct burden and procedural risk (based on patient-specific anatomy), can be used to make a final decision regarding EVT. The DISTAL trial investigators concluded that while EVT should not be standard for all, it “can still be considered for select peo ple on a case-by-case basis” given its safety profile. Our recommendations align with their philosophy. The Table summarizes the evidence.M3/M4—Recommendations• EVT for distal MCA (M3/M4)—EVT with mechanical devices is not recommended as a standard treatment for occlusions of the M3/M4 MCA branches (class III: no benefit; LOE B-randomized).• It is reasonable to enroll patients with M3/M4 occlu sions and disabling deficit in future RCTs examining the safety and efficacy of EVT using aspiration technique, small/adjustable stentrievers, or intra-arterial throm bolysis compared with best medical management.Rationale Across multiple randomized trials—including DISTAL, ESCAPE-MeVO, and interim DISCOUNT results— no improvement in 90-day functional outcomes was observed for patients with M3/M4 occlusions treated with EVT. Some evidence (DISCOUNT) even suggested a potential signal toward harm, including higher rates of intracranial hemorrhage. These findings are consistent with the small infarct volumes, low NIHSS scores, and favorable natural history typical of distal cortical branch occlusions. No RCT subgroup has demonstrated a clear clinical benefit. Practical Considerations EVT for all distal MCA occlusions cannot be justified. However, individualized use may be reasonable in rare cases where the deficit is clearly disabling (eg, aphasia, hemiparesis, severe visual deficit), IVT is contraindicated, or imaging demonstrates substantial at-risk tissue with minimal core. Vessel fragility and tortuosity increase procedural risk. Enrollment into ongoing DMVO trials is encouraged. The use of intra-arterial thrombolytics may be of benefit in select patients and continues to be investigated.ACA OCCLUSIONS (A2/A3)Isolated occlusions of the ACA beyond the A1 segment are relatively uncommon (≈1%–5% of acute ischemic stroke), but can lead to significant disability. The A2 seg ment, defined as the postanterior communicating artery segment, supplies the medial frontal lobes, including areas responsible for leg motor/sensory function (para central lobule), abulia, and motivation (medial frontal cor tex), and bladder function. Bilateral ACA strokes (if both A2s are affected, or one A2 in the presence of a single anterior communicating artery supplying both sides) can cause paraplegia with incontinence and profound abulia, which can be highly disabling. Unilateral A2/A3 occlusions often cause contralateral leg weakness more than arm/face and can cause frontal release behaviors or cognitive slowing. Some patients with unilateral ACA stroke compensate well if the other ACA via the anterior communicating artery provides collateral flow. Thus, clini cal presentation can range from mild leg weakness to akinetic mutism, depending on collateral circulation and the extent of infarct.Evidence High-level evidence for EVT in ACA is sparse, as these occlusions were not targeted in earlier EVT trials. In addi tion, the recent DMVO RCTs only included small ACA subgroups. In DISTAL, 30 patients (5.5%) had A2/ A3 occlusions, and no benefit from EVT was observed (odds ratio, 0.43 [95% CI, 0.10–1.83]). ESCAPE-MeVO enrolled 24 patients (4.5% with ACA occlusions) but did not report subgroup outcomes. DISCOUNT included 27 patients (17%) with ACA occlusions (including A1), and no subgroup results were available. The ORIENTAL MeVO trial included 66 patients with ACA occlusions, and in subgroup analyses, there was a trend toward improved outcomes, although it did not reach statistical significance (adjusted rate ratio, 1.23 [95% CI, 0.93– 1.69]). The DISTALS trial included 10 patients with ACA occlusions and was associated with no rates of sICH in this population. Outside of the limited evidence from the randomized trials, the best evidence for the ACA comes from obser vational comparisons and accumulated case series. The TOPMOST study (Treatment for Primary Medium Ves sel Occlusion Stroke) was a retrospective case-control analysis that included 110 matched patients with distal ACA occlusions. 51 The rate of favorable outcome (mRS score of 0–2) was 49% in both groups after propensityTable. Summary of Guideline Recommendations for EVT in Medium-Vessel Occlusions by Territory Vascular territory Recommendation COR LOE M2 (MCA division) EVT should be performed for disabling proximal and/or dominant M2 occlusions—with favorable imaging with CT, CTP, or MRI.IIa B-NREVT is reasonable in nondominant/codominant or distal M2 occlusions with severe clinical presentations (NIHSS score ≥6).IIb B-RRoutine EVT for nondominant or low-severity M2 occlusions is not recommended. Additional randomized trial data are needed.III A M3/M4 (Distal MCA) Routine EVT is not recommended/ EVT may be considered in select cases with severe deficits, favorable imag ing, and poor response to IV thrombolysis.III/ IIb B-R/ C-LD ACA (A2/A3) Routine EVT not recommended for isolated distal ACA occlusions. III B-NR EVT should be considered for patients with disabling deficits, large territory at risk, favorable imaging, and good baseline functional status.IIb B-NR PCA (P1/P2/P3) Routine EVT for isolated PCA occlusions not recommended. III B-NR EVT may be considered for patients with severe, disabling deficits or those unable to receive IV thrombolysis. IIb B-R COR: I=is recommended; IIa=is reasonable; IIb=may be considered; III=not recommended/no benefit (or harm). LOE: A=multiple RCTs or meta-analyses; B-R=single RCT or NR subgroup from RCT; B-NR=observational or registry studies; C-LD=LD or expert opinion. Where trial data for DMVO were neutral or negative, recom mendations are by necessity based on nonrandomized evidence and expert consensus, as reflected in the LOE. ACA indicates anterior cerebral artery; COR, Class of Recommendation; CT, computed tomography; CTP, computed tomography perfusion; DMVO, distal- and medium-vessel occlusion; EVT, endovascular thrombectomy; IV, intravenous; LD, limited data; LOE, Level of Evidence; MCA, middle cerebral artery; MRI, magnetic resonance imaging; NIHSS, National Institutes of Health Stroke Scale; NR, nonrandomized; PCA, posterior cerebral artery; R, randomized; and RCT, randomized controlled trial.matching, and excellent outcome (mRS score of 0–1) was ≈37.8% versus 33.3% (EVT versus medical). Mortal ity at 90 days was also similar (21.6% with EVT versus 30.8% with medical; P>0.05). Rates of successful recan alization were seen in 81% of cases, and the rate of sICH was only 2.1%. This was seen in MAD-MT (Multicenter Analysis of Distal Medium Vessel Occlusions: Effect of Mechanical Thrombectomy), where procedural success was 91% without a substantial improvement in functional outcome over BMT. 52 Several other observational com parisons and accumulated case series also demonstrate similar outcomes. 53–59 Taken together, these studies sug gest that EVT for distal ACA occlusions does not confer a clear benefit but also does not cause significant harm in experienced centers. It should be noted that many of the deficits caused by an ACA occlusion are behavioral (abulia, agitation, emotional lability, and cognitive decline), would not be captured in the mRS, and as such, compli cate assessing the benefit of EVT in these patients. 60• In acute ischemic stroke due to an occlusion of the distal ACA (A2/A3 segments), routine EVT is not recommended due to insufficient evidence dem onstrating clear benefit (class III: no benefit; LOE B-nonrandomized).• In patients with ACA occlusion with disabling deficits, large territory at risk, favorable imaging, and good baseline functional status, EVT may be considered on a case-by-case basis (class IIb; LOE B-nonrandomized).Rationale Evidence from the DMVO RCTs (DISTAL, ESCAPE MeVO, DISCOUNT) includes only small ACA subgroups, none showing benefit. ORIENTAL-MeVO demonstrates a trend towards benefit. Observational studies—including TOPMOST-ACA (Treatment for Primary Medium Vessel Occlusion Stroke — Anterior Cerebral Artery subgroup) and several multicenter registries—demonstrate high recanalization rates but no improvement in functional outcomes with EVT over medical therapy. Mortality and sICH rates seem similar between groups, with random ized data (DISTALS) suggesting technical feasibility with no additional harm but no proven superiority. Practical Considerations Management of distal ACA occlusions should generally favor best medical therapy, with individualized decision making reasonable in select patients. Rationale Although no randomized trial has shown clinical benefit, multiple observational cohorts as well as the DISTALS randomized trial confirm that EVT for A2/A3 occlusions is technically feasible, achieves high rates of success ful recanalization, and does not increase hemorrhagic complications relative to medical management. ACA occlusions were included in the ORIENTAL-MeVO trial, which as a whole, demonstrated a benefit in patients with high NIHSS scores. Patients with clinically severe ACA syndromes—such as profound leg-dominant weakness, akinetic mutism/abulia, bilateral ACA involvement, or per fusion imaging demonstrating a large at-risk territory with limited core—may derive meaningful benefit from reperfu sion. These presentations behave more like proximal ante rior circulation strokes, for which EVT may be beneficial. Practical Considerations Individualized EVT may be most appropriate for those with disabling symptoms likely to cause long-term depen dence, those ineligible for IV thrombolysis, and those with imaging confirming salvageable tissue. Bilateral ACA supply variants or hemodynamically vulnerable territories may further support intervention. When possible, patients with distal ACA occlusions should be enrolled in ongoing DMVO or ACA-specific randomized trials to strengthen the evidence.PCA P1 TO P3 SEGMENTS OCCLUSIONSIsolated PCA occlusions are considered DMVOs and most often present with visual field defects, cortical blindness, alexia without agraphia, or visual-cognitive dis turbances. Although proximal P1 occlusions can cause more disabling midbrain/thalamic syndromes, most iso lated P2/P3 strokes result in primarily visual field deficits, which vary in their functional impact. Classification of P1 occlusions may vary; some centers classify a dominant P1 as a large vessel requiring urgent attention, while oth ers include P1 in DMVO analyses. For the purposes of these guidelines, P1 occlusions are included in DMVO discussions. The clinical spectrum is broad, making indi vidualized assessment essential when considering EVT. Evidence Across the 2025 DMVO randomized trials—ESCAPE MeVO, DISTAL, and DISCOUNT-PCA—occlusions rep resented a small proportion of enrolled patients. None of these trials demonstrated a functional benefit of EVT for P2/P3 subgroups, and subgroup analyses from ESCAPE-MeVO and DISTAL showed no improvement in 90-day disability outcomes with EVT. DISCOUNT did not report PCA-specific results. More recently, ORIENTAL MeVO included 54 patients with PCA occlusions with a trend towards benefit in the PCA subgroup (adjusted rate ratio, 1.37 [95% CI, 0.95–2.00]), whereas the DISTALS trial included 32 patients with PCA occlusions and dem onstrated improved successful reperfusion and no sICH. Observational and multicenter studies provide addi tional clarity. The PLATO study—the largest analysis of isolated PCA strokes—found no improvement in disabil ity outcomes with EVT compared with medical therapy, although EVT was associated with greater early NIHSS score improvement and higher rates of complete visual recovery. 61 The TOPMOST registry and other retrospec tive cohorts similarly demonstrate that EVT is technically feasible with high recanalization rates, but without consis tent functional benefit (as measured by mRS). The TOP MOST study suggested a possible advantage in patients with more severe strokes (NIHSS score ≥10) or in those ineligible for intravenous thrombolysis. 62 Meta-analyses demonstrated no improvement in functional outcomes and suggested a potential increase in mortality among EVT-treated patients. 63 Overall, nonrandomized evidence reinforces that EVT for distal PCA occlusion remains of uncertain benefit and should be applied cautiously. 64–67 It should be noted that measuring outcomes in PCA occlu sion with tools such as mRS may not fully capture the extent of disability and/or recovery in these patients. Based on these data, EVT for isolated P2/P3 occlu sions should not be routinely performed. A selective, indi vidualized approach may be reasonable for patients with clearly disabling deficits, such as in patients with cortical blindness, dense hemianopia affecting independence, or significant midbrain/thalamic involvement, as EVT in this population has been found beneficial in some studies. 61,68 Lower infarct burden, favorable anatomy, and availability for thrombolytics should be key consideration points dur ing EVT decision-making. Patients with mild or rapidly improving symptoms, or those with isolated visual field deficits unlikely to impair long-term functional recovery, should generally be treated medically. Enrollment into clinical trials evaluating EVT for distal posterior circula tion occlusions is preferred when available.• EVT is not recommended as a routine treatment for isolated PCA occlusions (class III: no benefit; LOE B-nonrandomized).Rationale Subgroup analyses from the DMVO RCTs, ESCAPE MeVO, DISTAL, and DISCOUNT, show no functional ben efit of EVT in P1 to P3 occlusions. The overall neutral/ negative findings of these trials, combined with higher hemorrhage rates observed in the EVT arms of some studies, provide no supportive signal for routine inter vention in isolated distal PCA occlusions. However, the recent results of ORIENTAL-MeVO, a positive trial with a signal towards benefit in the PCA subgroup, as well as the DISTALS trial, which demonstrated safety, should be taken into consideration. Observational evidence, including large cohorts such as PLATO, TOPMOST, and other multicenter registries, demonstrates high technical recanalization success but no consistent improvement in 90-day disability, and some meta-analyses suggest a possible increase in mortality among EVT-treated patients. Together, these data indicate that EVT is technically feasible but may not improve outcomes when applied broadly. Practical Considerations Routine EVT for all P2/P3 occlusions is not indicated, especially in those patients with small, nondisabling visual field deficits, rapidly improving symptoms, or imag ing showing limited tissue at risk. P2/P3 strokes may produce visual deficits with variable functional impact. Patients may achieve adequate functional recovery with the best medical therapy alone. Consideration of EVT should be avoided in patients with small, nondisabling visual field deficits, rapidly improving symptoms, or imag ing showing limited tissue at risk.• EVT for isolated PCA occlusions (P1, P2, or P3 segments) may be considered in selected patients who present early, exhibit severe neurological defi cits significantly impacting quality of life, or who are ineligible for intravenous thrombolysis (class IIb; LOE B-randomized).Rationale Although randomized data are neutral, several retrospec tive multicenter studies and propensity-matched com parative cohorts (eg, PLATO, 69 TOPMOST-PCA) suggest that patients with severe or disabling presentations— including cortical blindness, dense hemianopia impacting independence, or proximal PCA occlusions with midbrain or thalamic involvement—may derive greater benefit from reperfusion. These studies showed high recanalization success and no excess symptomatic ICH when EVT was performed in high-severity cases. Technical feasibil ity combined with observational outcome data supports individualized decision-making. This is corroborated by the recent findings from the ORIENTAL-MeVO trial and the safety signal in DISTALS. Practical Considerations EVT may be reasonable in patients with clearly disabling visual or diencephalic syndromes (eg, cortical blindness, dense hemianopia, midbrain/thalamic involvement), in those ineligible for IV thrombolysis, or when imaging demonstrates substantial salvageable tissue. Enrollment in prospective DMVO trials is encouraged.The Table summarizes the guideline recommendations for EVT in medium and distal vessel occlusions, accord ing to vascular territory. Each recommendation includes the Class of Recommendation and LOE.
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PublishedJun 9, 2026
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