Network Optimization - Ep.1/2 - SLICE Worldwide 2022

Current options to expanding thrombectomy access in your catchment area

Introduction:

Endovascular treatment (EVT) for large vessel occlusion (LVO) acute ischemic stroke has been proven to be highly efficient in reducing disability and may also reduce mortality (at least for basilar artery occlusions). However, several papers have shown that access to EVT is still far from optimal even in highly developed countries with many comprehensive stroke centers. It has been shown that the chance to benefit from thrombectomy is lower for patients living in rural areas or in smaller cities that do not have comprehensive stroke centers. Indeed, the farer away one is from a comprehensive stroke center the higher the likelihood that one will not be eligible for endovascular treatment and the higher the likelihood that a stroke victim will remain with important disability. Given this data several options have been explored to reduce the inequality of access to treatment in several regions. This is a quick review of potential options to expand thrombectomy access in your region. 

Mothership vs drip-ship models [1]:

1. In urban and densely populated areas emergency medical service (EMS) strategies should be in place to guide potential stroke victims towards a comprehensive stroke center if the delay is less than 30 min or 60 min.
   
   
2. To select these patients using a validated pre-hospital scale to identify potential LVO stroke is recommended.
   
   
3. When travel times to the comprehensive stroke centers are greater than 60 min, there is not enough evidence to choose between the two options. The RACECAT study was negative, patients delivered at local primary hospitals had a higher chance of receiving tPA (60.4% vs. 47.5%) and 16% recanalized by the time they arrived in the EVT capable center. In contrast patients randomized directly to the EVT centers had higher rates of thrombectomy (48.8% vs 39.4%). There were no differences in functional outcome at three months.
   
   
4. However, interpreting the results of the RACECAT trial depends on the capabilities of stroke systems of care to deliver fast-efficient and safe acute tPA treatment and door-in-door-out times to patients with acute ischemic stroke. When primary stroke centers, are fast in delivering tPA (33 min door to needle times) and fast in sending eligible patients towards thrombectomy – drip-and-ship is an option. However, if primary hospitals are less fast, less safe and incur significant delays by-passing them may be an option. 

Flying doctor model [2]:

1. A non-randomized controlled trial from Germany evaluated the option of flying interventionalists to peripheral centers while the patient is being prepared for thrombectomy in these centers vs. transferring patients from primary stroke centers towards the comprehensive stroke center.
   
   
2. Flying the interventionalist resulted in a 90 min improvement in door to groin time, however this was not associated with improved outcomes (the study lacked power to demonstrate differences in outcomes).  
   
   
3. This model may be employed safely in regions that have the necessary infrastructure
   1) readily available helicopter services;
   2) readily available angio-suite equipment and anesthesia in primary stroke centers; However, there is no high-quality evidence that it improves outcomes and may be associated with additional important costs.
    
4. Comprehensive stroke centers aiming to rely on transferring the physician need also to consider the fact that the interventionalist on duty will not be available for other procedures during the time associated with the transfer and that his work-schedule must be blocked during the time he is on shift. This may require a very big interventional team in the comprehensive stroke center. 

Setting up new thrombectomy capable centers:

1. High volume primary stroke centers with available angio-suites and peripheral radiology teams may be trained and guided by the comprehensive stroke centers in assuming local treatment of LVO stroke patients.
   
   
2. Local peripheral radiologists, cardiologists or neurologists may be trained to perform mechanical thrombectomy in the comprehensive stroke center and gradually assume the coverage in the peripheral hospital once they are ready.
   
   
3. For difficult cases the use of digital real-time modern proctoring technologies may enhance their confidence and may improve outcomes. Interventionalists from the comprehensive stroke centers may guide them step by step through-out the procedure using this modern proctoring systems.
   
   
4. When interventional teams in the comprehensive stroke center permit it, a regional model may be established in which daily one interventionalists rotates to a high-volume peripheral center and is ready to perform thrombectomy during working hours. This may permit the training of the local team and may offer a chance to patients experiencing a stroke during daytime.

Conclusion:

Currently tested and available methods to reduce the inequality of access to EVT treatment are heterogenous and depend on each region. There is no perfect model and the only certainty that currently exists is that each region has work-out a model that fits best its geography, economy, population, and medical resources. Obtaining a fast and efficient triage of stroke patients in a region may be the most valuable intervention that a comprehensive stroke center can make to improve outcomes in his catchment area.

1.          Pérez de la Ossa, N.; Abilleira, S.; Jovin, T.G.; García-Tornel, Á.; Jimenez, X.; Urra, X.; Cardona, P.; Cocho, D.; Purroy, F.; Serena, J.; et al. Effect of Direct Transportation to Thrombectomy-Capable Center vs Local Stroke Center on Neurological Outcomes in Patients With Suspected Large-Vessel Occlusion Stroke in Nonurban Areas: The RACECAT Randomized Clinical Trial. JAMA 2022, 327, 1782–1794, doi:10.1001/jama.2022.4404.

2.          Hubert, G.J.; Hubert, N.D.; Maegerlein, C.; Kraus, F.; Wiestler, H.; Müller-Barna, P.; Gerdsmeier-Petz, W.; Degenhart, C.; Hohenbichler, K.; Dietrich, D.; et al. Association Between Use of a Flying Intervention Team vs Patient Interhospital Transfer and Time to Endovascular Thrombectomy Among Patients With Acute Ischemic Stroke in Nonurban Germany. JAMA 2022, 327, 1795–1805, doi:10.1001/jama.2022.5948.