Understanding Atherothrombotic Large Vessel Occlusion in Acute Stroke

Acute ischemic stroke management has evolved rapidly, yet treating patients with atherothrombotic large vessel occlusion presents major therapeutic dilemmas. Currently, emergency endovascular therapy serves as the premier standard of care for acute large vessel revascularization. However, clinicians actively debate whether bridging intravenous thrombolysis prior to thrombectomy provides meaningful clinical benefits in atherosclerotic stroke. In standard cardioembolic strokes, bridging therapy often softens the fresh fibrin-rich clot and facilitates mechanical extraction. In contrast, intracranial atherosclerotic disease involves chronic plaque inflammation, severe vessel stenosis, and superimposed platelet-rich thrombi. Consequently, traditional thrombolytic agents such as alteplase might behave unpredictably in this fragile vascular environment. Furthermore, emerging evidence demonstrates that intracranial plaque architecture differs fundamentally from clean embolic occlusions. Therefore, indiscriminate bridging thrombolysis may expose vulnerable patients to serious procedural hazards without enhancing final recanalization rates. Identifying the exact occlusion mechanism early during presentation has thus become crucial for optimizing patient outcomes. Neurologists and neurointerventional teams must carefully balance the theoretical benefits of rapid clot dissolution against the tangible risk of fatal reperfusion hemorrhage.

The RESCUE Registry: Evaluating Pre-Thrombectomy Thrombolysis

To resolve persistent controversies surrounding bridging therapy, investigators performed a comprehensive subanalysis of the multicenter RESCUE AT-LVO registry across Japan. The study cohort specifically comprised acute ischemic stroke patients undergoing endovascular therapy for atherothrombotic large vessel occlusion. Researchers categorized patients into two distinct mechanistic cohorts based on catheter angiography findings. The intracranial group consisted of 336 patients suffering from acute in situ atherothrombotic occlusions. Meanwhile, the tandem group comprised 233 patients presenting with artery-to-artery embolism originating from cervical carotid artery stenosis or occlusion. Within each mechanistic cohort, clinicians compared patients receiving bridging alteplase against those undergoing primary endovascular intervention alone. The primary efficacy outcome was functional independence at ninety days, defined as a modified Rankin Scale score of zero to two. Additionally, critical safety outcomes tracked any intracranial hemorrhage and all-cause mortality within ninety days of stroke onset. By utilizing multivariable logistic regression models, investigators adjusted for baseline neurological deficits, patient age, and procedural variables. Consequently, this rigorous nationwide registry delivers vital real-world evidence regarding modern acute neurovascular revascularization strategies.

In Situ Occlusions: Increased Hemorrhage Risk and Zero Benefit

The registry findings demonstrated unequivocal hazards when clinicians administered intravenous alteplase before mechanical thrombectomy for in situ intracranial disease. Among the 336 patients with intracranial atherothrombotic occlusions, 99 individuals received intravenous thrombolysis prior to endovascular therapy. Notably, rates of favorable functional independence did not improve with bridging alteplase. Specifically, 51.1 percent of thrombolyzed patients achieved favorable recovery compared to 47.6 percent in the direct thrombectomy cohort. The adjusted odds ratio was 1.18, confirming no statistically significant therapeutic benefit from thrombolysis. In stark contrast, safety endpoints deteriorated significantly in patients receiving pre-treatment thrombolytic medication. Any intracranial hemorrhage developed in 10.1 percent of the alteplase stratum versus only 3.8 percent of non-thrombolyzed individuals. Consequently, bridging therapy nearly tripled the odds of bleeding, generating an adjusted odds ratio of 2.98. Moreover, ninety-day mortality climbed to 6.4 percent in thrombolyzed patients compared to 1.3 percent in direct intervention cases. This alarming increase yielded an adjusted odds ratio of 4.66 for mortality. Thus, bridging alteplase dramatically elevates life-threatening complications without conferring measurable neurological advantages in in situ occlusions.

Tandem Lesions: Contrasting Dynamics in Carotid Pathology

Interestingly, patients presenting with tandem atherothrombotic occlusions exhibited distinctly different clinical responses compared to the intracranial cohort. The tandem cohort included 233 individuals who suffered cervical carotid stenotic disease alongside downstream cerebral vessel occlusions. Among these patients, 88 individuals received intravenous alteplase prior to endovascular therapy. Primary functional outcomes at ninety days revealed no statistically significant differences between the two treatment groups. Both cohorts achieved comparable recovery rates, demonstrating that thrombolysis provided no discernible functional edge. However, unlike the in situ group, bridging alteplase did not increase hemorrhagic complications or mortality in tandem presentations. Intracranial hemorrhage frequencies and ninety-day mortality rates remained statistically equivalent between thrombolyzed and non-thrombolyzed groups. Emboli originating from extracranial plaques often consist of softer fibrin-rich components that respond somewhat differently to enzymatic breakdown. Nonetheless, clinicians gained no functional recovery by infusing systemic lytic agents before mechanical revascularization. Therefore, while bridging therapy avoids overt excess harm in tandem lesions, it yields no clear therapeutic superiority over direct mechanical thrombectomy in clinical practice.

Biological Mechanisms and Revised Clinical Pathways

Several critical pathophysiological mechanisms explain why bridging alteplase produces severe harm during in situ atherothrombotic interventions. First, fixed atheromatous stenoses consist primarily of dense lipid cores, smooth muscle proliferation, and fibrous caps rather than purely dissolvable fibrin. Systemic thrombolysis cannot resolve severe structural luminal narrowing. Second, interventionalists navigating microcatheters through ulcerated, fragile atheromas frequently induce mechanical endothelial injury. When systemic thrombolytic activity coincides with procedural vessel trauma, catastrophic extravasation often ensues. Third, managing in situ atheroma often necessitates rescue angioplasty or emergent intracranial stenting. Because newly deployed intracranial stents provoke acute platelet activation, operators frequently administer potent glycoprotein IIb/IIIa inhibitors or oral antiplatelets. Combining pre-procedural alteplase with urgent intraprocedural antiplatelet therapies exponentially amplifies fatal bleeding hazards. Consequently, emergency neurovascular teams should modify diagnostic protocols. Utilizing acute multimodal computed tomography angiography helps clinicians identify intracranial atherosclerotic disease early. When teams suspect in situ atherothrombotic occlusion, skipping intravenous alteplase and proceeding directly to the catheterization suite represents the safest strategy. Ultimately, avoiding bridging thrombolysis optimizes patient safety and prevents severe procedural mortality during emergent endovascular recanalization.

Why did intravenous alteplase increase mortality in in situ intracranial occlusions?

Intravenous alteplase significantly elevated mortality by tripling intracranial hemorrhage rates in patients with inflamed, friable atherosclerotic vessels. Furthermore, mechanical manipulation during thrombectomy traumatizes diseased arterial walls. When combined with systemic lytic activity and subsequent antiplatelet therapy required for intracranial stenting, the risk of catastrophic bleeding and fatal reperfusion hemorrhage rises sharply.

Did bridging thrombolysis benefit patients with tandem carotid occlusions?

No, bridging intravenous alteplase failed to improve ninety-day functional independence in patients with tandem atherothrombotic occlusions. However, unlike in situ intracranial disease, thrombolysis did not significantly increase intracranial hemorrhage or mortality in the tandem cohort. Clinicians must still balance this lack of efficacy against bleeding risks during emergent carotid stenting.

How should clinicians identify in situ intracranial occlusions before thrombectomy?

Clinicians can identify underlying in situ intracranial stenosis using multimodal computed tomography angiography, magnetic resonance angiography, and detailed source images. Key radiological indicators include tapered arterial occlusion, absence of hyperdense vessel signs, severe intracranial calcification elsewhere, and robust leptomeningeal collateral circulation on baseline neuroimaging scans before urgent catheterization.

Disclaimer: This content is for informational and educational purposes only and should not be taken as professional medical advice. Always consult with a qualified healthcare provider for specific medical guidance. Refer to the latest local and national guidelines for clinical practice.

References

1. Hayashi H et al. Effect of intravenous alteplase before endovascular therapy for atherothrombotic stroke-related large vessel occlusion: subanalysis of the RESCUE AT-LVO registry. Stroke Vasc Neurol. 2025 Dec 23. doi: 10.1136/svn-2024-003983. PMID: 40250865.


2. Uchida K, Yamagami H, Sakai N, et al. Endovascular therapy for acute intracranial large vessel occlusion due to atherothrombosis: multicenter historical registry. J Neurointerv Surg. 2024;16(9):884-891. doi: 10.1136/jnis-2023-020524.


3. Yoshimoto T, Yamagami H, Sakai N, et al. Association of perioperative P2Y12 inhibitor administration with outcomes for tandem occlusion: RESCUE AT-LVO sub-study. Front Neurol. 2024;15:1475882. doi: 10.3389/fneur.2024.1475882.