Letter to the editor,regarding “Rescue therapy after failed thrombectomy in medium/distal vessel occlusions: A retrospective analysis of an international,multi-center registry” recently published by Anastasiou Aikaterini and colleagues

We found the article by Anastasiou et al. ¹ insightful and commend the authors for their study showing successful rescue stenting for distal and medium vessel occlusions (DMVOs) after failed mechanical thrombectomy (MT) in acute ischemic stroke. Rescue stenting with intravenous anti-GPIIbIIIa achieved 84% recanalization, surpassing the 72%–75% rates from recent randomized controlled trials (RCTs) on MT and best medical treatment for DMVOs.^2,3

Given that rescue stenting offers higher recanalization rates than MT, why not consider primary stenting for DMVOs? Stenting without thrombectomy avoids the obvious risk related to navigation with the largest possible aspiration catheter in small cerebral vessels or the risk of elongation and rupture of transmedullar arteries related to straightening of the course of distal cerebral arteries during retraction on a stentriever. It may be argued that rescue stenting in the current study was achieved in relation to intracranial atherosclerotic disease (ICAD) and not to a thrombus. The authors report that an underlying ICAD was suspected in all patients in whom MT remained unsuccessful. The main argument is a relatively low proportion of patients having a cardiembolic etiology, as reflected by the 10.3% incidence of atrial fibrillation. This raises the question of whether outcomes may be less favorable with a higher proportion of cardioembolic strokes, as existing literature indicates that their fibrin- and platelet-rich composition results in a denser, more compact thrombus structure, thereby increasing resistance to reperfusion therapies. Furthermore, MT failure doesn’t necessarily indicate ICAD, as MT can fail independently. The location at medium and distal vessel is unusual for ICAD that mostly affects proximal cerebral vessels. Finally, whether the acute occlusion is related to a thrombus or to ICAD remains irrelevant as diagnosis cannot be assessed with certainty and regardless of the etiology, the achieved recanalization rate after rescue stenting was high in this study.

A concern with rescue stenting is the small size of the targeted artery. The modified Rankin Scale distribution at 90 days shows better outcomes in patients with M2 occlusions compared to those with M3/M4/ACA and PCA occlusions. There may be bias in comparing these groups since ACA and PCA occlusions are often linked with M3 and M4 segments. However, if rescue stenting of M2 occlusions leads to better outcomes than M3 and M4, despite a smaller volume of hypoperfused brain, this suggests that MT in more distal locations may offer limited benefits, questioning the efficacy of rescue stenting in M3 and M4 segments.

One argument against rescue stenting is the discrepancy between high recanalization rates and low functional independence, with only 32% of patients achieving functional independence. In comparison, RCTs on distal thrombectomy^2,3 reported functional independence rates of 35%–43%, even with best medical treatment alone or with MT. Therefore, recanalization rate is not the sole prognostic indicator. The anti-GPIIbIIIa medication used with rescue stenting to prevent acute in-stent thrombosis may explain the higher rate of symptomatic intracranial hemorrhage (sICH), approximately 10%, in this study. Post-stenting antiplatelet regimens, such as tirofiban or cangrelor combined with aspirin, need further investigation. The varying reports on hemorrhagic complications with tirofiban in thrombectomy patients ⁴ require validation in larger cohorts. However, it remains uncertain whether the observed bleeding rate in this study is attributable to the combination of infarcted brain tissue and dual antiplatelet therapy (DAPT), or to smaller arterial injuries incurred during unsuccessful MT attempts prior to rescue stenting, alongside DAPT. The latter hypothesis further supports the potential benefit of primary rescue stenting over rescue stenting following MT failure.

Currently, no universally accepted quality standards exist for performing MT, nor are there clear guidelines on when to stop thrombectomy attempts. There is also a lack of consensus on evaluating thrombectomy techniques and determining the optimal sequence for their use. This lack of evidence is particularly evident in DMVOs, where treatment is less straightforward compared to large vessel occlusions (LVOs). Although no RCTs have been conducted, growing evidence supports improved outcomes after rescue stenting in LVOs. A recent meta-analysis found that rescue stenting had a higher likelihood of achieving favorable outcomes without significantly increasing the risk of sICH. ⁵ While rescue stenting can be effective when MT fails in LVO cases, its success depends on careful patient selection, operator expertise, and the use of specialized devices. In contrast, there is no evidence supporting MT’s benefit for DMVOs, raising questions about the potential of rescue stenting as an alternative. Additionally, the role of intra-arterial fibrinolytics, including tenecteplase, should also be considered as a treatment option.