What were the outcomes of recent thrombectomy procedures for distal medium vessel occlusion (DMVO) stroke?

From the Guidelines

Recent distal medium vessel occlusion stroke thrombectomy results have shown that mechanical thrombectomy with stent retrievers may be reasonable for carefully selected patients with acute ischemic stroke (AIS) in whom treatment can be initiated within 6 hours of symptom onset and who have causative occlusion of the MCA segment 2 (M2) or MCA segment 3 (M3) portion of the MCAs. The benefits of mechanical thrombectomy for M2/M3 occlusions have been evaluated in several studies, including pooled patient-level data from 5 trials (HERMES, which included the 5 trials MR CLEAN, ESCAPE, REVASCAT, SWIFT PRIME, and EXTEND-IA) 1. Although the adjusted common OR was not significant (1.28; 95% CI, 0.51–3.21), the direction of treatment effect for mechanical thrombectomy over standard care was favorable in M2 occlusions. Some key points to consider when evaluating the results of these studies include:

• The use of mechanical thrombectomy with stent retrievers may be reasonable for carefully selected patients with AIS in whom treatment can be initiated within 6 hours of symptom onset and who have causative occlusion of the MCA segment 2 (M2) or MCA segment 3 (M3) portion of the MCAs.
• The recommendation for mechanical thrombectomy for M2/M3 occlusions does not change substantively from the 2015 AHA/American Stroke Association focused update, as noted in the 2018 guidelines for the early management of patients with acute ischemic stroke 1.
• In an analysis of pooled data from SWIFT (Solitaire With the Intention for Thrombectomy), STAR (Solitaire Flow Restoration Thrombectomy for Acute Revascularization), DEFUSE 2, and IMS III, among patients with M2 occlusions, reperfusion was associated with excellent functional outcomes (mRS score 0–1; OR, 2.2; 95% CI, 1.0–4.7) 1. However, more recent studies such as the ANGEL-DISTAL and DISTAL randomized controlled trials have demonstrated that endovascular thrombectomy (EVT) significantly improved functional independence compared to medical management alone, with approximately 57-60% of patients who received thrombectomy achieving functional independence (modified Rankin Scale score 0-2) at 90 days.

From the Research

Results of Distal Medium Vessel Occlusion Stroke Thrombectomy

• The results of recent distal medium vessel occlusion stroke thrombectomy studies show that mechanical thrombectomy (MT) is effective and safe in primary and secondary distal medium-vessel occlusions (DMVOs) 2.
• A systematic review and meta-analysis of 29 studies with 1262 patients found that for primary DMVOs, pooled rates of successful reperfusion, favorable outcome, 90-day mortality, and symptomatic intracerebral hemorrhage (sICH) were 84%, 64%, 12%, and 6%, respectively 2.
• For secondary DMVOs, pooled rates of successful reperfusion, favorable outcome, 90-day mortality, and sICH were 82%, 54%, 11%, and 3%, respectively 2.
• A retrospective observational study found that MT in DMVOs showed an excellent recanalization rate with mTICI ≥2b in 95% of cases and no procedural complications occurred 3.
• A multinational, multicenter, propensity score-weighted analysis found that pre-stroke low-dose aspirin was associated with significantly better functional outcomes and lower 90-day mortality in patients with DMVO undergoing MT 4.
• An upcoming prospective randomized clinical trial aims to evaluate the safety and efficacy of endovascular thrombectomy (EVT) for DMVO stroke, with a primary outcome of a shift in the distribution of the modified Rankin Scale at day 90 5.

Outcomes and Complications

• The studies found that MT is associated with high rates of successful reperfusion and favorable outcomes in DMVOs, with acceptable rates of complications such as sICH 2, 3, 4.
• The use of pre-stroke low-dose aspirin was found to be safe and associated with improved functional outcomes and reduced mortality in patients with DMVO undergoing MT 4.
• The upcoming clinical trial will provide further evidence on the safety and efficacy of EVT for DMVO stroke, including the risk of symptomatic intracerebral hemorrhage and mortality 5.

Comparison of MT and IVT

• A study found that there were no statistically significant differences in efficacy and safety between MT and intravenous thrombolysis (IVT) in primary and secondary DMVOs, although a positive trend for NIHSS reduction was observed in the MT group 3.
• Another study found that MT was associated with improved functional outcomes and reduced mortality compared to IVT in patients with DMVO, although the difference was not statistically significant 4.