Stentriever thrombectomy for stroke within and beyond the time window

Abstract

Endovascular therapy (EVT) for stroke due to large vessel occlusion has been recently approved, changing dramatically the outcome of these patients, who otherwise would have a dismal outcome. However, there are patients automatically excluded from EVT because they arrive beyond the therapeutic time window. Traditionally, the time window (TW) for EVT has been 8 hours but the recent guidelines shortened the window to 6 hours. The TW is defined as the time from symptom onset to the time of groin puncture. In patients in whom the stroke onset is unclear either because the stroke occurred while sleeping or because the patient is unable to tell the onset because is aphasic on unconscious, and no witness is available, the onset is considered the last time the patient was seen normal. These patients often fall outside the window (OTW), because are too late to be treated. Other patients that are too late to be treated are those who, despite having a clear time of onset, arrive OTW. However, there is growing evidence showing that the speed at which the ischemia evolves after an arterial occlusion, varies significantly among individuals. Thus, while in some patients the arterial territory is infarcted in 6 hours, in other, the infarct might not be established after 10 hours. This concept radically challenges the current time-based approach, which establishes whether a patient should be treated or not based on the time from onset provided there is not a large area of infarcted tissue. Interestingly, the tissue-based approach disregards the time from onset. Consequently, the criteria to decide whether to treat a patient or not, would be to image the brain to find out if there is viable tissue, if so, treatment should be carried forward irrespective of the time since stroke onset. There are ongoing trials to prove this hypothesis, and non-controlled studies have been published showing that patients treated OTW have comparable safety and favorable outcomes than those treated within the window. However, those studies were performed with first generation devices and some refer to anterior and posterior circulation strokes. Regarding new generation strategies, stentrievers (ST) have demonstrated higher rates of recanalization and better outcomes. Current guidelines recommend the use of ST. The primary aim of this work was to compare the outcomes and safety of patients OTW with stroke due to anterior circulation (AC) occlusion treated with EVT with ST and selected by neuroimaging with the safety and outcomes of patients WTW. From a total of 468 patients, 292(63.4%) were patients WTW and 176 (37.6%)OTW. The group OTW was divided in two subgroups according to onset: unknown time of onset (UKO) in 113 (24.1%) patients and known onset but late presenters (KO-LP) in 63 (13.5%) patients. These subgroups could not be merged because p statistical analysis showed that they were not comparable, thus, the results had to be presented separately and compared with the WTW group. Regarding outcome, there were no significant differences good outcome at 3 months, with rates of 49% in WTW, 42.2%% in UKO and 37.3% in KO-LP. Regarding safety, there were no significant differences in symptomatic intracranial hemorrhage across groups (6.2%WTW, 2.7%UKO y 9.5%KO-LP). These findings support the tissue- based approach in patients with stroke due to AC occlusion treated with EVT using ST, and selected by neuroimaging, until the results of the randomized trials arrive. According to our study, a positive result would have a great impact on at least, one out of three patients that arrive OTW and are currently left untreated.

Date of Award	27 Jul 2016
Original language	English
Awarding Institution	Hospital de la Santa Creu i Sant Pau
Supervisor	Marc Ribó Jacobi (Director) & Antonio Dàvalos Errando (Director)