Mechanical Thrombectomy in Acute Ischemic Stroke Beyond the Time of Window

Background Expanding time window using the emerging technologies for mechanical thrombectomy can improve chances of achieving successful thrombectomy and improve clinical outcome in patients that would have only received conservative treatment. The aim of this work is to evaluate the effectiveness and safety of endovascular therapy within 24 hours of symptom onset and to compare clinical outcome of endovascular therapy and standard medical therapy at the end of 3rd month.

Subjects and Methods:

This is a multicenteric case-control clinical trial (Ain shams and Aswan university hospitals), comparing clinical improvement and mortality/morbidity in patients presenting with acute ischemic stroke stroke caused by occlusion of the proximal middle cerebral artery (M1 segment) or Internal carotid artery (distal ICA segment) within 24 hours from symptom onset.

Onset of stroke was defined as time they were last known to be well. Ischemic stroke is characterized by the sudden loss of blood circulation to an area of the brain, resulting in a corresponding loss of neurologic function. It included 57 patients with acute ischemic stroke due to large vessel occlusion (LVO) admitted either to neurology department of Ain shams university hospitals or Aswan university hospitals between during the period from Jan 2019 and August 2019

All patients were subjected to the following:

A) Clinical assessment:

Full history taking with special emphasis upon: Age and Sex of the patient, onset of symptoms; onset is defined as the point in time the patient was last seen well, presence of vascular risk factors, namely: diabetes mellitus, hypertension, cardiac diseases, dyslipidemia and smoking. History of receiving drugs prior to arrival to the hospital, especially anti-coagulants, and anti-platelets & IV thrombolytics.

Complete general and neurological assessment including: complete general examination including blood pressure measurement using mercurial sphygmomanometer and random blood sugar assessment, neurological examination on admission with NIHSS assessment to determine initial NIHSS, neurological deficit was measured using (NIHSS) obtained on discharge and on day 90 with the modified Rankin Scale (mRS) measured on discharge and after 3 months (Bonita and Beaglehole, 1988). A standard 12-lead ECG to delineate presence of ischemic changes or arrhythmias was also done Routine ER laboratory investigations including: complete blood count and coagulation profile and serum urea and creatinine.

Hypertension was defined as self-report of hypertension with antihypertensive medication use, and/or systolic blood pressure greater than or equal to 140 mm Hg, and/or diastolic blood pressure greater than or equal to 90 mm Hg. Diabetes was defined as being on treatment for diabetes by self-report with antidiabetic drugs and/or having a fasting glucose level greater than or equal to 126 mg/dL, plasma glucose ≥ 200 mg/dl 2 h after a 75-g oral glucose load as in a glucose tolerance test, or glycated hemoglobin (HbA1C) ≥ 6.5%. Patients with past or current history of smoking were categorized as smokers. Dyslipidemia was defined as serum total cholesterol (TC) > 240, serum LDL-c > 160, serum triglycerides (TAG) > 200 and/or serum HDL-c < 40 (WHO 2006).

B) Radiological assessment:

Early ischemic changes and collateral circulation were assessed with the Alberta stroke program for early computed tomography (CT) ischemic score (ASPECTS) and with computed tomography angiography (CTA), magnetic resonance angiography (MRA) or digital subtraction angiography (DSA) for localization of the LVO.

N.B: a CT scan was routinely performed between 24 and 36 h after treatment or before in case of any neurological worsening (≥4-point increase in NIHSS score) occurred.

Procedure of endovascular intervention:

All patients in the 1st group (vascular intervention group) underwent primary thrombectomy with either the Trevo (TR) stent or the Solitaire (ST) stent (according to the availability) within the first 24 hours of symptoms onset.

All procedures were performed under the investigator's institutional mild sedation protocol. Some cases needed general anesthesia.

Favorable outcome was defined as achieving functional independence "mRS of 0,1or 2 in 3 months, poor outcome was defined as mRS of 3-5. Treatment starting is defined as femoral puncture.

Vascular recanalization was defined as thrombolysis in cerebral ischemia (TICI) score. Successful recanalization was defined as TICI grade 2b to 3.

Established device-related complications, namely, vascular perforation, arterial dissection, or embolization, were systematically collected. Symptomatic intracranial hemorrhage was defined as a hemorrhagic transformation on the 24-h computed tomography (CT) scan related to the deterioration in the patient's clinical condition in the judgment of the clinical investigator.Statistical analysis:

Statistical analysis was performed using the Statistical Package for the Social Sciences (IBM SPSS statistics V23).

Adjusted for age group (1=<70, 2= ≤70 years), Sex (female=0 or male=1), Diabetes mellitus (yes=1 or no=0), Hypertension (yes=1 or no=0),Cardiac (AF=1, IHD=2, Rheumatic heart=3, normal =4, AF +IHD =5) Smoking (yes=1 or no=0), Dyslipidemia (yes=1 or no=0), (B, correlation coefficient; CI, confidence interval; OR, odds ratio; SE, standard error; Wald statistics for logistic regression analysis.

The outcome of interest was the change in NIHSS and mRS scores throughout 90 days. Continuous variables are expressed as mean + standard deviation and categorical variables with percentage of occurrence. For comparison of continuous variables, the Mann-Whitney test was used between-group comparison. Chi Square test was used for analysis of proportions. A p Value <0.05 was the threshold for statistical significance.

Inclusion criteria

• Patients Aged between 18 and 80 years old.
• Patients with acute ischemic stroke due to occlusion of the MCA or ICA suitable for endovascular treatment, as evidenced by CTA, MRA or angiogram.

• Patients with symptoms onset between 6- 24 hours from arrival to the time of femoral puncture.

Exclusion criteria

A. Clinical exclusion criteria:

• Patients known to have hemorrhagic diathesis, coagulation factor deficiency, or oral anticoagulant therapy with INR > 2.0.
• Patients with a pre-existing neurological or psychiatric disease that would confound the neurological evaluations; mRS score before the onset of stroke must be ≤ 1.

B. Neuroimaging exclusion criteria:

• Patients with hypodensity on CT accounting to an ASPECTS score of <7.
• Patients with CT or MRI evidence of hemorrhage (the presence of micro-bleeds is allowed).
• Patients Significant mass effect with midline shift on CT brain.
• Subjects with occlusions in multiple vascular territories (e.g., bilateral anterior circulation, or anterior/posterior circulation) on CT brain.