Carotid Shunt and Stroke: Systematic Review with ☸️SAIMSARA.



DOI: 10.62487/saimsara9d60e2fd

Author: saimsara.com


Review Stats
Identification of studies via EPMC (titles/abstracts) Identification Screening Included Records identified:n=5058Records excluded:n=0 Records assessed for eligibilityn=5058Records excluded:n=4511 Studies included in reviewn=547 PRISMA Diagram generated by ☸️ SAIMSARA
⛛OSMA Triangle Effect-of Predictor → Outcome Carotid Shunt  →  stroke Beneficial for patients ΣN=23681 (3%) Harmful for patients ΣN=48070 (7%) Neutral ΣN=653883 (90%) 0 ⛛OSMA Triangle generated by ☸️SAIMSARA
Outcome-Sentiment Meta-Analysis (OSMA): (LLM-only)
Frame: Effect-of Predictor → Outcome • Source: Europe PMC
Outcome: stroke Typical timepoints: peri/post-op, 30-day. Reported metrics: %, CI, p.
Common endpoints: Common endpoints: complications, mortality, functional.
Predictor: Carotid Shunt — exposure/predictor.




1) Introduction
Carotid artery disease, primarily characterized by stenosis of the internal carotid artery (ICA), is a significant cause of ischemic stroke. Surgical intervention, primarily carotid endarterectomy (CEA), and endovascular approaches like carotid artery stenting (CAS), aim to prevent stroke by removing or stabilizing atherosclerotic plaques. A critical aspect of these procedures, particularly CEA, is maintaining adequate cerebral perfusion during the temporary clamping of the carotid artery. Carotid shunts are employed to bypass the clamped segment, ensuring blood flow to the brain and potentially mitigating intraoperative cerebral ischemia. However, the optimal strategy for shunt use—routine, selective, or no shunting—remains a subject of ongoing debate, with concerns regarding both the benefits of preventing hypoperfusion and the risks associated with shunt insertion, such as embolization or injury. This paper systematically synthesizes recent evidence to clarify the complex relationship between carotid shunt use and stroke outcomes.

2) Aim
This review aims to synthesize the current evidence regarding the impact of carotid shunt use on stroke rates and related neurological outcomes in patients undergoing carotid revascularization procedures, and to identify key areas for future research.

3) Methods
This systematic review was conducted using an Autonomous Multilayer AI Research Agent (SAIMSARA) to identify, extract, and synthesize information from a structured extraction summary.

3.1 Eligibility criteria: Original studies, including cohort studies, randomized controlled trials (RCTs), case series, mixed-design studies, experimental studies, and synthetic/simulation studies, were included. Editorials, conference papers, and review articles were excluded from the primary synthesis of quantitative results but informed the broader discussion.

3.2 Study selection: Studies were identified through an upstream screening process using the keyword gate "Carotid Shunt and Stroke." The provided structured extraction summary represents the output of this selection.

3.3 Risk of bias: The included studies predominantly comprised retrospective cohort studies and mixed-design studies, which are inherently susceptible to selection bias and confounding. Case series and single-patient reports provide limited generalizability. While some randomized controlled trials were included, the overall evidence base exhibits heterogeneity in methodology, patient populations, and reported outcomes, suggesting a moderate to high risk of bias across the synthesized literature.

3.4 Synthesis: Autonomous multilayer AI research agent: keyword normalization, retrieval & structuring, and paper synthesis (see SAIMSARA About section for details).

4) Results

4.1 Study characteristics: The included studies primarily consisted of retrospective cohorts and mixed-design studies, often focusing on patients undergoing carotid endarterectomy (CEA) or carotid artery stenting (CAS) for symptomatic or asymptomatic carotid stenosis. Populations ranged from single case reports to large registries of over 100,000 patients [12, 58]. Follow-up periods varied widely, from immediate perioperative outcomes and 30-day assessments to long-term evaluations extending up to 10 years [46, 231].

4.2 Main numerical result aligned to the query:
The perioperative or 30-day stroke rate reported in studies where a carotid shunt was utilized or indicated ranged from 0% [368, 493] to 9.5% [531]. The median reported stroke rate associated with shunt use was 1.9%. However, the evidence regarding the net effect of shunting on stroke rates is contradictory. Some studies indicated that shunt use was associated with higher stroke rates or adverse events [24] (asymptomatic stroke 2.5% vs 0.55% without shunt), [33] (routine shunting 4.0% vs selective 1.1%), [64] (intraoperatively-indicated shunting 1.9% vs 0.7% no shunting), [170] (shunting associated with higher 30-day stroke or death), [220] (shunt placement strong predictor of perioperative strokes), and [531] (stroke higher in shunted cases 9.5% vs 0.9% non-shunted). Conversely, other studies reported a reduction in stroke rates with shunt use [48] (routine shunting reduced stroke-related death and stroke within 30 days), [449] (selective shunting 0.5% major stroke vs routine 4.4%), and [493] (0% cerebral infarctions in shunted group vs 8% unshunted). Several large studies found no significant difference in stroke rates between shunted and non-shunted groups or different shunting strategies [12, 23, 43, 250].

4.3 Topic synthesis:



5) Discussion

5.1 Principal finding: The median perioperative or 30-day stroke rate reported in studies involving carotid shunt use was 1.9% (range 0% to 9.5%), but the evidence regarding whether shunting increases, decreases, or has no significant impact on stroke risk is highly contradictory across the literature [12, 24, 48, 493, 531].

5.2 Clinical implications:


5.3 Research implications / key gaps:


5.4 Limitations:


5.5 Future directions:


6) Conclusion
The median perioperative or 30-day stroke rate reported in studies involving carotid shunt use was 1.9% (range 0% to 9.5%), with highly contradictory evidence regarding its net effect on stroke risk. This review highlights that while shunts are intended to prevent cerebral ischemia during carotid artery clamping, their use is associated with a wide range of stroke outcomes, with some studies suggesting benefit and others indicating increased risk. The heterogeneity of study designs and inconsistent outcome reporting significantly limits the certainty of conclusions. Future large-scale, prospective randomized controlled trials with standardized protocols for shunt indication and comprehensive neurological outcome assessments are critically needed to clarify the optimal role of carotid shunts in stroke prevention.

References
SAIMSARA Session Index — session.json

Figure 1. Publication-year distribution of included originals
Figure 1. Publication-year distribution of included originals

Figure 2. Study-design distribution of included originals
Figure 2. Study-design distribution

Figure 3. Study-type (directionality) distribution of included originals
Figure 3. Directionality distribution

Figure 4. Main extracted research topics
Figure 4. Main extracted research topics (Results)

Figure 5. Limitations of current studies (topics)
Figure 5. Limitations of current studies (topics)

Figure 6. Future research directions (topics)
Figure 6. Future research directions (topics)