Abstract
Mechanical thrombectomy (MT) is indicated for patients with acute ischemic stroke resulting from large vessel occlusion (LVO). At Hull Royal Infirmary (HRI), the MT service is available from 08:00 h to 16:00 h, Monday to Friday. Consequently, many patients who present outside of those times are denied a chance of having this treatment. The objective of this audit was to detect the percentage of patients who had presented out of hours and managed to have MT and to identify why the remaining proportion of patients did not receive this treatment. A total of 35 patients with anterior circulation LVO who presented out of hours and on weekends were included in this audit. Of these, only six patients (17%) received MT. Selection of those patients was favoured by their early-morning presentation shortly before the opening of the MT service at 08:00 h. Thus, a substantial number of patients presenting with LVO out of hours were not considered for MT. This could be attributed to inadequate communication between staff. Initiation of an in-hospital protocol could facilitate communication between stroke physicians and neuroradiologists and provide a pathway for consideration of such patients for late-window MT.
Background
Current guidelines for the management of acute ischaemic stroke recommend mechanical thrombectomy (MT) for patients who present within 24 h of symptom onset, with the use of specific imaging-based selection criteria for patients presenting during later time windows.1,2 The unavailability of sufficient resources and expertise means that MT is often only available for limited periods during the working week.
At our institution (Hull Royal Infirmary; HRI), the MT service is only available from 08:00 h to 16:00 h, Monday to Friday, leaving the remainder of the working day and weekends uncovered. Thus, the presentation of patients with large vessel occlusion (LVO) at the weekends or out of hours precludes them from having this effective treatment.
Many tertiary centres in the UK are aiming to expand the MT service gradually to cover 24 h, including weekends; however, this is challenged by a lack of staff and logistic barriers.3 It is unclear whether it would be better to expand hours to cover more of the weekday or to open the service during the weekends from 08:00 h to 16:00 h.
A plan was launched at HRI to extend the service on weekdays until 20:00 h, accepting the risk that the provision of this expanded service could be impacted by shortage of staff. Although extension of the MT service to cover 24 h a day, 7 days a week remains a distant goal, late-window MT using advanced imaging could grant a practical and an acceptable solution to this problem. Nonetheless, many patients who present out of hours are not reassessed or rescanned to be considered for this procedure when the service becomes available next morning.
To address this issue, we designed a retrospective audit to (1) identify the percentage of patients presenting with LVO who underwent MT when they presented out of hours or at weekends; and (2) determine why the remaining patients were not considered for late-window MT. This audit provides a baseline for designing a local imaging protocol to aid suitable patient identification.
Methods
Eligibility
Inclusion criteria (all of these criteria must apply):
Patients presented between 16:00 h and 08:00 h Monday to Thursday (MT available after 08:00 h the next working day).
Patients presented to hospital at any time on a Sunday (MT would be available the following Monday).
Onset of symptoms was <24 h from the next available time for MT.
Premorbid pre-stroke Modified Rankin Score (mRS) ≤3.
National Institutes of Health Stroke Scale (NIHSS) ≥6.
Evidence of anterior circulation LVO on imaging.
Exclusion criteria:
Premorbid mRS >3.
NIHSS <6.
Post-lysis NIHSS <6 (if the patient had been thrombolysed).
No evidence of LVO on imaging/low mismatch on perfusion.
Onset of symptoms >24 h from the next available time for MT.
Patients presented on Saturday or after 16:00 h on Friday (because MT service would not be available within the following 24 h).
Data collection
We reviewed 333 case notes and imaging of patients with acute ischaemic stroke who presented when MT was not available. We excluded 287 patients because their imaging did not show any evidence of LVO. Of the remaining 46 patients (representing 13% of the total patients reviewed), we excluded another 11 patients because they did not meet the eligibility criteria (Table 1). The remaining 35 patients were included in the audit.
Number of patients who did not meet the eligibility criteria
Ethical approval and consent to participate
This report forms part of an ongoing audit project registered at HRI. The project was registered with the hospital audit department (Code 2022.045) and, as such, no further formal ethical approval was required.
Results
In total, data from 35 patients (13 men (37%)) and (22 women (63%)) with a mean age of 76 years were analysed. Their initial NIHSS was 6–15 in 17 patients (48%), 16–20 in eight patients (22%), and >20 in 10 patients (30%) (Fig 1).
Number of patients with LVO who were candidates for MT categorised according to their NIHSS score on initial presentation, and whether they underwent MT. LVO = large vessel occlusion; MT = mechanical thrombectomy; NIHSS = National Institutes of Health Stroke Scale.
When thrombectomy was not available, 22 patients (63%) underwent computed tomography (CT) angiography on presentation. Only four patients underwent CT perfusion, all of whom at presented to hospital within 3 h of thrombectomy being available.
Intravenous (IV) thrombolysis was administered to 20 patients (57%), a quarter of whom (five patients) underwent an additional MT. Median NIHSS was 14.5 before and 10 after thrombolysis.
Overall, only six patients (17%) underwent MT. All six patients presented within 4 h before the next available time for MT (five patients had a known stroke onset and one patient was of unknown onset, although CT perfusion showed a salvageable penumbra) (Fig 2).
Number of patients with LVO who were candidates for MT categorised according to the duration from the onset of stroke to the point at which MT became available and whether they underwent MT. LVO = large vessel occlusion; MT = mechanical thrombectomy.
Out of the six patients who underwent MT, four patients were discharged from hospital with a mRS of 0 or 1. Two patients died at the age of 90 and 84 years because of a large cerebral infarction.
Discussion
Globally, stroke is the second-leading cause of death and the third-leading cause of death and disability combined.4 In the UK, the incidence of stroke is 100,000 per year, meaning that, every 5 min, one person will develop a stroke. Over the next 2 decades, the incidence and prevalence of stroke is expected to increase by 60% and 120%, respectively.5 Thus, measures to reduce the disabling effect of stroke should be implemented.
The introduction of MT has revolutionised stroke medicine and has led to a marked improvement in the prognosis of patients with stroke when used in the appropriate setting. Pertaining to this, application of MT within 6 h of the onset of stroke demonstrated significantly improved outcomes at 90 days as determined by a lower mRS (number needed ot treat (NNT) = 7.4 in the MRCLEAN trial).6 By using specific imaging criteria, this 6-h window was extended to 16 h in the DEFUSE3 trial7 and to 24 h in the DAWN trial.8 The ensuing favourable outcome after late-onset MT was ascribed to good collateral circulation and slow rate of growth of the ischaemic core in a substantial number of patients with LVO.9
The MT service at HRI covers North and East Yorkshire and North Lincolnshire. From April 2017 until March 2022, ∼2.5% of all patients admitted with ischaemic stroke underwent MT (Table 2). However, our audit suggests that several patients who presented out of hours were not reassessed or rescanned for consideration of late-window MT. The reasons for this could be attributed to inadequate communication between the stroke and neuroradiology teams and the absence of an in-hospital protocol to guide the process of management of patients who could be potential candidates for late-window thrombectomy. In addition, patients with LVO are not always considered a priority that should be managed immediately when the MT service becomes available. Additionally, some patients are not considered for late-window MT because they have already been given IV thrombolysis.
Number of patients who had MT at HRI from April 2017 to March 2022
Thus, we have designed a local protocol to offer a structured and clear pathway that would guide and direct the relevant departments and staff to provide appropriate management for such patients. In this protocol, we considered a time window of 6–16 h and the advanced imaging criteria based on the DEFUSE3 trial (Fig 3).
A local protocol designed to provide a pathway for staff involved in the management of patients with LVO ischaemic stroke presenting when MT is not available. CT = computed tomography; CTA = computed tomography angiography; CTP = computed tomography perfusion; LVO = large vessel occlusion; mRS = modified Rankin Score; MT = mechanical thrombectomy; NIHSS = National Institutes of Health Stroke Scale.
Advanced imaging, such as CT and magnetic resonance imaging (MRI) perfusion studies are important in selecting candidate patients for late-window MT. However, the unavailability of, or difficult access to, such imaging in many hospitals could preclude considering patients for this effective treatment. Interestingly, a recent retrospective study that compared non-contrast CT (using the Alberta stroke program early CT score (ASPECT) score) versus MRI and CT perfusion in patients with late-presentation anterior circulation stroke resulting from LVO showed no difference in the clinical outcome between groups.10 This might open the door for considering more patients for late-window MT by easing and expediting the process of scanning them using non-contrast CT instead of advanced imaging techniques.
Conclusion
Extended-window MT using advanced imaging techniques can and should be utilised to benefit patients with LVO stroke who present out of hours when the MT service is not available. A protocol agreed among the stroke team, radiologists and interventionists will help establish this practice and facilitate accessibility to this service for those who need it.
Acknowledgements
The authors would like to thank Dr Rayessa Rayessa (consultant stroke medicine) and Mrs Andrea Dennison (SSNAP Coordinator) for facilitating and providing the data for this audit.
- © Royal College of Physicians 2023. All rights reserved.
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