Risk factors for infarct growth and haemorrhagic or oedematous complications after endovascular treatment - a literature review

Introduction: Acute ischaemic stroke (AIS) is caused by significant disturbances in the cerebral bloodflow (CBF) that lead to brain ischaemia and eventually result in irreversible brain tissue damage. The main goal of its treatment is to restore bloodflow to the areas at risk of necrosis. Intravenous thrombolysis (IVT) and mechanical thrombectomy (MT) are the mainstay of current therapy, with the latter being widely employed in selected patients with radiologically proven large vessel occlusion (LVO). Despite convincing evidence of its efficacy, up to half of patients undergoing endovascular treatment (EVT) still do not achieve a beneficial functional outcome; this is mainly due to unfavourable brain tissue sequelae. Therefore, factors associated with known adverse brain changes, such as larger infarct size or haemorrhagic and oedematous complications, should be adequately addressed.

Objective: To review the available literature describing AIS brain tissue outcome assessed by computed tomography (CT) and/ or magnetic resonance imaging (MRI) in patients undergoing MT treatment. Additionally, to evaluate the association of post-MT tissue changes with short- and long-term prognosis.

Material and methods: We searched the PubMed, Scopus, EMBASE, and Google Scholar databases according to established criteria.

Results: We found a total of 264 articles addressing the most common types of AIS tissue sequelae after EVT (i.e. MT with or without IVT as bridging therapy) by brain CT and MRI. These were: follow-up infarct volume (FIV), cerebral oedema (COD) and haemorrhagic transformation (HT). As the next step, 37 articles evaluating factors associated with defined outcomes were selected. Several non-modifiable factors such as age, comorbidities, pretreatment neurological deficit, and collateral circulation status were found to affect stroke tissue sequelae, to varying degrees. Additionally, some factors including time to treatment initiation, selection of treatment device, and periprocedural systemic blood pressure, the modification of which can potentially reduce the occurrence of an unfavourable tissue outcome, were identified. Some recently revealed biochemical and serological parameters may play a similar role.

Conclusions: The identification of factors that affect post-MT ischaemic area evolution may result in studies assessing the effects of their modification, and potentially improve clinical outcomes. Modifiable parameters, including periprocedural systemic blood pressure and some biochemical factors, may be of particular importance.