Optimizing the Referral Pathway for Mechanical Thrombectomy: Evidence-Based Perspectives on Mothership vs. Drip-and-Ship Models

Highlights

• The ‘Mothership’ strategy (direct transport to a comprehensive stroke center) is associated with higher odds of 90-day functional independence (mRS 0-2) compared to ‘Drip-and-Ship’.
• Meta-regression identifies a 43-minute onset-to-groin puncture delay as the critical threshold beyond which the Mothership strategy provides significantly superior outcomes.
• Intravenous thrombolysis (IVT) administered in the late window (>4.5 hours) before interhospital transfer remains effective and safe, potentially improving recanalization rates.
• Innovative models such as ‘Flying Intervention Teams’ and prehospital teleconsultation significantly improve rural stroke care efficiency and long-term functional results.

Background

Acute ischemic stroke due to large vessel occlusion (AIS-LVO) is a medical emergency where outcomes are strictly time-dependent. While mechanical thrombectomy (MT) has become the gold standard, the optimal prehospital referral strategy remains a subject of intense clinical debate. Currently, two primary models exist: the ‘Mothership’ model, where patients are transported directly to an endovascular-capable Comprehensive Stroke Center (CSC), and the ‘Drip-and-Ship’ (DS) model, where patients first receive intravenous thrombolysis at a local Primary Stroke Center (PSC) before being transferred for MT. As the global incidence of stroke rises, particularly in aging and rural populations, refining these triage protocols is essential to mitigate long-term disability.

Key Content

Comparative Efficacy and Functional Outcomes

A landmark systematic review and meta-analysis by Guo et al. (2026), encompassing 42 studies and 25,005 patients, provides definitive insights into these strategies. The analysis revealed that the Mothership strategy significantly improved the likelihood of achieving functional independence at 90 days (mRS 0 to 2) with an odds ratio (OR) of 1.15 (95% CI 1.03–1.29). Interestingly, no significant differences were observed between the two models regarding broader functional outcomes (mRS 0 to 3), successful recanalization rates (OR 1.03), symptomatic intracranial hemorrhage (sICH) (OR 0.84), or 90-day mortality (OR 0.99). These findings suggest that while direct transport offers a marginal benefit in achieving optimal recovery, both systems provide comparable safety profiles.

The 43-Minute Threshold and Time Sensitivity

The choice between Mothership and Drip-and-Ship is often dictated by geography. Research published in the Journal of the American Heart Association (2026) suggests that the Mothership model becomes clearly superior when the interhospital transfer process in the DS model adds more than approximately 43 minutes of delay to the onset-to-groin puncture time. Beyond this threshold, the benefit of early IVT at a local hospital is outweighed by the loss of viable penumbra caused by the delay in mechanical reperfusion. Conversely, in regions where distance to a CSC exceeds 65 km, patients often default to the DS model, emphasizing the need for regional logistics optimization.

Innovations in Rural and Regional Stroke Systems

Bridging the urban-rural disparity in stroke care has led to several innovative service models:

• Flying Intervention Teams (FIT): In Bavaria, Germany, dispatching a neurointerventional team to peripheral hospitals (FIT model) was associated with significantly better 12-month functional outcomes compared to traditional patient transfer (mRS 3 vs 4).
• Prehospital Teleconsultation: Studies from Alberta, Canada, demonstrated that EMS-initiated teleconsultation (the ‘Stroke Speedometer’ metric) increased the likelihood of direct transport to CSCs and subsequent MT (aRR 2.25).
• AI Decision Support: Implementation of AI-based imaging software (e.g., Brainomix 360) in the UK NHS was associated with a 100% relative increase in MT rates at evaluation sites, facilitating faster identification of LVO in primary centers.

Late Window Interventions and Safety

New evidence challenges the traditional 4.5-hour limit for IVT in the context of transfer. Multicenter cohort data (2025/2026) indicate that IVT initiated beyond 4.5 hours prior to transfer is associated with higher recanalization rates (OR 8.69) and better 3-month outcomes without increasing hemorrhage risk. Furthermore, Direct Transfer to the Angiography Suite (DTAS) has been explored to bypass ER imaging. While simulation studies show DTAS can save nearly 18 minutes in door-to-puncture time, the DIRECT ANGIO trial in France was halted early due to an increased risk of sICH (15% vs 0%), suggesting that bypassing initial CT may not be safe for all suspected LVO patients.

Expert Commentary

The ‘Mothership vs. Drip-and-Ship’ debate is shifting from a ‘one-size-fits-all’ approach to a personalized triage model. The meta-analytical evidence suggests that the Mothership strategy should be prioritized for patients within a reasonable travel radius of a CSC. However, the DS model remains a vital component of stroke care for rural populations. The biological rationale rests on the ‘penumbra-save’ theory: for some patients, the immediate administration of IVT at a PSC can initiate recanalization or stabilize the clot, whereas for others, the delay in reaching MT is catastrophic.

Critical limitations in current research include the lack of randomized controlled trials (RCTs) directly comparing these pathways; most data originate from observational cohorts subject to selection bias. Future guidelines should incorporate community socioeconomic status, as current expansion of stroke centers has shown uneven benefits, with disadvantaged communities seeing less improvement in MT access despite closer proximity to new centers.

Conclusion

While the Mothership strategy offers a slight edge in achieving high-level functional independence, the Drip-and-Ship model remains a robust and safe alternative when geographic barriers exist. The integration of prehospital tele-neurology, AI imaging, and potentially ‘flying’ medical teams can mitigate the inherent delays of the DS model. Future research must focus on identifying the specific patient phenotypes (e.g., based on collateral status or biomarker-based POCT) that would benefit most from direct bypass versus initial local stabilization.

References

• Guo L et al. Mothership and Drip-and-Ship Strategies in Mechanical Thrombectomy for Acute Ischemic Stroke. Ann Emerg Med. 2026. PMID: 42084585.
• Zhang X et al. Mothership Versus Drip-and-Ship Models in Acute Stroke Care: A Time-Sensitive Meta-Analysis. J Am Heart Assoc. 2026. PMID: 41717865.
• Leclerc X et al. Safety and efficacy of direct versus conventional transfer to angiography suite (DIRECT ANGIO). Lancet Neurol. 2026. PMID: 41864232.
• Boulanger M et al. Intravenous Thrombolysis Use in the Late Time Window Before Interhospital Transfer. JAMA Neurol. 2026. PMID: 41324934.
• Czlonkowska A et al. Outcomes at a Thrombectomy-Capable Stroke Center in Poland. Life (Basel). 2026. PMID: 41752940.