Mobilisation After Endovascular Stroke Treatment

Title Mobilisation After Endovascular STROke treatment (MAESTRO): A prospective multicentre cohort study

Background and Rationale Stroke remains one of the leading causes of death and long-term disability worldwide. Each year, approximately 12-15 million people experience a stroke, with ischaemic stroke accounting for around two-thirds of cases. In Sweden alone, more than 26,000 individuals are affected annually, and the majority of patients are elderly. Beyond mortality, stroke often results in significant disability and dependency, requiring extensive rehabilitation and long-term care.

Over the past decade, endovascular thrombectomy (EVT) has revolutionised treatment for acute ischaemic stroke (AIS) caused by large vessel occlusion (LVO). Randomised controlled trials have demonstrated substantial improvements in functional outcome for patients undergoing EVT compared to medical therapy alone, with benefits extending up to 24 hours after stroke onset. EVT has therefore become standard of care for selected patients with LVO.

While EVT has improved prognosis, it also introduces new challenges in the acute post-procedural phase. Most procedures are performed via femoral artery access, necessitating a period of strict bed rest to reduce the risk of access site haematoma (ASH). Patients often recover neurologically within hours, however, and may wish to mobilise earlier than current routines allow. The optimal timing of mobilisation after EVT remains unclear. Early mobilisation may reduce complications of immobility, but may also increase the risk of ASH. Conversely, prolonged bed rest may lower the risk of ASH but increases the risk of venous thromboembolism (VTE), infections such as pneumonia and urinary tract infection (UTI), and delirium. These complications are common after stroke, associated with worse outcomes, and prolong hospital stay.

Reported incidence of ASH varies widely, from 1% to 10%, likely due to inconsistent definitions and underreporting.

VTE after EVT has been reported in more than a quarter of patients in some studies, particularly among those with severe motor deficits or prolonged procedures. Post-stroke pneumonia affects more than one third of thrombectomy-treated patients and is independently associated with increased mortality and reduced independence. Delirium is a frequent complication among acute stroke patients, characterised by altered consciousness, disorganised thinking or disorientation, psychomotor disturbances, and circadian rhythm disruption, and is associated with worse outcomes. However, evidence regarding delirium after mechanical thrombectomy (MT) remains limited, as most previous studies were conducted in mixed stroke cohorts with few MT cases or predate the thrombectomy era. Together, these complications underscore the clinical importance of identifying safe and effective mobilisation strategies.

Despite the relevance of these issues, few studies have systematically investigated mobilisation after EVT. Available evidence is limited, definitions vary across studies, and results are contradictory. There is currently no consensus on when mobilisation should be initiated after EVT, leaving clinicians with considerable uncertainty. This knowledge gap has direct implications for patient safety, recovery, and the development of evidence-based care protocols.

Aim and Research Questions The overarching aim of this study is to investigate how the timing of mobilisation after EVT influences the occurrence of complications. The study will also describe the frequency, timing, and risk factors of complications related to mobilisation and immobilisation.

Research questions:

1. What is the frequency of ASH, VTE, delirium, and infections after EVT, and which factors are associated with increased risk?
2. How does timing of first mobilisation (12 vs 24 hours) affect the incidence of these complications?
3. When do these complications occur in relation to EVT completion and first mobilisation? Methods Study design This is a prospective multicentre cohort study conducted at two hospitals with different mobilisation routines after EVT: a Swedish centre where patients are mobilised at approximately 12 hours post-procedure, and a Finnish centre where mobilisation occurs after approximately 24 hours. The design allows for systematic comparison of the two care protocols.

Participants and eligibility All adult patients (≥ 18 years) undergoing endovascular thrombectomy (EVT) for acute ischaemic stroke (AIS) at either participating centre will be consecutively screened for eligibility according to the inclusion and exclusion criteria listed below.

Inclusion criteria

• Adult patient (≥ 18 years)
• Undergoing EVT for acute ischaemic stroke Exclusion criteria
• Patient residing outside the hospital's primary catchment area (due to difficulties following data when patient is transferred to primary hospital)
• Inability of both patient and next of kin to understand the study information, making informed consent impossible (applicable to Finland)
• Patients who remain in the intensive care unit (ICU) for more than a few hours post-procedure, as key early post-EVT events (e.g., mobilisation timing, access-site observation, and early complications) would not be captured due to lack of CRF registration in ICU settings
• For outcome-specific analyses: patients with pre-existing venous thromboembolism (VTE), delirium, or infection at the time of inclusion will be excluded from the corresponding outcome analyses Recruitment and inclusion will be performed consecutively by dedicated and trained staff at each centre according to a standardised protocol (see Appendix 2, Participant Inclusion Form. Informed consent will be obtained from the patient or, when necessary, from a legally authorised representative or next of kin (see Appendix 3, Informed Consent Form).

In Sweden, presumed consent will be applied in rare cases where neither the patient nor a next of kin can provide consent, for example due to severe aphasia or unconsciousness. In such cases, inclusion will occur since participation poses no additional burden or risk, and only when every reasonable effort will have been made to obtain informed consent as soon as possible. No patient who expresses unwillingness or hesitation will ever be included.

Exposure and outcomes The primary exposure is the timing of first mobilisation after EVT, defined by local routine and recorded prospectively for each patient. Mobilisation includes sitting at the bedside with feet on the floor or in a chair/wheelchair, standing, or walking. Positioning in bed with elevated head of bed does not count as mobilization in this study. The primary outcome is ASH. Secondary outcomes include VTE (deep vein thrombosis or pulmonary embolism), infections (pneumonia or urinary tract infection), and delirium. The timing of these events in relation to EVT completion and mobilisation will be documented when available.

Data collection

Data collection is based on three complementary components:

1. prospective case report forms (CRF) completed by clinical staff during hospitalisation,
2. retrospective extraction from electronic health records (EHR)
3. registry data from Riksstroke and EVAS (only applicable to Sweden). All data will be retrospectively transferred into REDCap.

The prospective CRF (see Appendix 1, CRF Prospective monitoring) includes:

• Timing, type, duration, and initiator of first mobilisation and whether mobilisation was interrupted due to clinical deterioration (single entry)
• Time of occurrence of ASH, including grading of haematoma severity (grade 1-3), the patient's mobility level at the time of onset (lying still in bed, moving in bed, sitting, standing, or walking), and whether the haematoma was detected at onset or later during subsequent care (single entry)
• Three daily limb inspections for signs of DVT, supplemented by Wells Score when indicated. Any use of compression devices is also recorded.
• Delirium screening three times daily using the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU).

Prospective data will be registered for as long as the patient remains admitted to the stroke unit, but for a maximum of five days, after which registration will stop.

Retrospective variables are obtained primarily from EHR, supplemented by national quality registries when not available in EHR (applicable for Sweden). These include demographics, comorbidities, medications, stroke severity, radiological findings, EVT-procedural details, blood pressure variability, infections (laboratory markers, antibiotic use, discharge diagnoses), VTE (discharge diagnoses or imaging reports), length of stay, discharge destination, functional status (Modified Rankin Scale [mRS] at 3 months), and mortality.

In Finland, due to national legislation requiring informed consent prior to data collection, early clinical data may in rare cases be retrieved retrospectively after inclusion and consent. This is possible as relevant parameters are already routinely documented within the local stroke care programme. It should be emphasised, however, that the study is primarily prospective, and any retrospective retrieval will only serve to capture early indicators of complications occurring before consent could be obtained.

Sample size and analysis A preliminary sample size calculation, assuming an ASH incidence of 10% in Finland and 20% in Sweden, indicated that approximately 400 patients (200 per site) are required to detect a statistically significant difference with α = 0.05 and power = 80%. This estimate is based on available literature and current clinical practice. Descriptive statistics will be used to summarise baseline characteristics and outcome frequencies. Categorical variables will be presented as counts and percentages, and continuous variables as means with standard deviations or medians with interquartile ranges.

Associations between mobilisation timing and complications will be analysed using multivariable logistic regression models, adjusting for potential confounders such as age, stroke severity, comorbidities, and procedural factors. Time-to-event analyses (Cox regression) may be applied where exact timing data are available. Subgroup analyses may be performed depending on data quality and sample size. Missing data will be handled using appropriate statistical methods depending on the extent and pattern of missingness.

Ethical considerations This study is observational and does not alter clinical care. Patients receive treatment according to the standard routines of each hospital. Prospective assessments, such as delirium screening, limb inspection, and ASH grading, are non-invasive, take only a few minutes, and entail no additional risk or discomfort for the patient. Data will be pseudonymised and stored in REDCap on secure EU servers, with access restricted to authorised research staff. All handling of personal data will comply with the General Data Protection Regulation (GDPR) and Karolinska Institutet's information security policies.

Significance This study addresses a critical knowledge gap in post-thrombectomy stroke care. By systematically comparing two mobilisation routines and documenting the frequency, timing, and risk factors of major complications, the study will generate evidence to guide safer and more individualised mobilisation protocols after EVT. The results may contribute to reducing complication rates, improving functional outcomes, and informing future clinical guidelines. Furthermore, the findings will provide a valuable basis for future scientific publications and for advancing the evidence base in stroke nursing and post-EVT care.