Large Artery Occlusion Treated in Extended Time With Mechanical Thrombectomy Trial

The LATE-MT trial aims to determine that compared with standard medical care without MT, performing MT in a time window that exceeds 24 hours after last seen well, is superior on the functional outcome in AIS patients due to LVO who have been carefully selected by clinical and imaging criteria. The secondary aims include comparing with standard medical care without MT, to determine whether performing MT exceeding 24 hours of last known well is safe on the risks of any ICH, sICH, and any SAE. Other secondary aims include early improvement in neurological recovery as measured by NIHSS scores at 7 days; successful recanalization rate; imaging measurements of infarct size; death or major disability (mRS 3-6); separately on death and disability (mRS 3-5); HRQoL using Euro-QoL EQ-5D questionnaire; utility-weighted modified Rankin scale scores; duration of hospitalization; residence; and hospital service costs.

Inclusion criteria

• Age ≥18 years
• Present 24-72 hours of stroke onset or last seen well
• Clinical diagnosis of AIS due to anterior circulation LVO (from internal carotid artery (ICA) extracranial segment to middle cerebral artery (MCA) M1 and M2 segment) on brain imaging
• National Institute of Health stroke scale (NIHSS) ≥6 at randomisation
• Viable cerebral tissue on computerized tomography perfusion (CTP) assessed: infarct core volume <50 mL, mismatch ratio ≥1.8, and mismatch volume ≥15 mL
• Written informed consent (by patient or proxy, according to local requirements)

Exclusion criteria

Clinical Exclusion Criteria

• Considered unlikely to benefit from trial (e.g. advanced dementia, major pre-stroke disability (prior modified Rankins scale (mRS) ≥2), high likelihood of early death), as judged by the responsible treating clinician
• Major co-morbid disease that could interfere with outcome assessments and follow-up (e.g. cancer, severe heart failure, kidney failure)
• Pregnancy
• Unable to undergo a CTP
• Known allergy to iodine, heparin, anaesthesia, or other definite contraindication to receiving endovascular treatment (EVT) procedure
• Seizures at stroke onset or before randomization and baseline NIHSS scores cannot be accurately determined
• Baseline blood glucose of <50 mg/dL (2.78 mmol/L) or >400 mg/dL (22.20 mmol/L)
• Baseline platelet count < 50,000/uL
• Known hereditary or acquired hemorrhagic diathesis, coagulation factor deficiency; recent oral anticoagulant therapy with International normalized ratio (INR) >3
• Severe, sustained hypertension that can not be controlled by medication (systolic BP >220 mmHg or diastolic BP >120 mmHg)
• Presumed septic embolus, suspicion of bacterial endocarditis
• EVT attempted after stroke onset
• Unlikely to participate in follow-up assessments
• Currently participating in another trial that may affect outcomes.
• Any other condition that, in the opinion of the investigator will pose a significant hazard to the subject if participating in the trial.

Neuroimaging Exclusion Criteria

• Intracranial hemorrhage (ICH), including parenchymal hemorrhage, ventricular hemorrhage, subarachnoid hemorrhage, and subdural/exsanguination
• Evidence of intracranial malignant tumor
• Significant mass effect with midline shift
• Aortic dissection
• Intracranial stent implanted in the same vascular territory
• Any other condition that may affect EVT procedure, like the tortuous vascular path the device is difficult to reach the target position or difficult to recover
• Occlusions in multiple vascular territories confirmed on Computerized tomography angiography (CTA)/ Magnetic resonance imaging angiography (MRA) (e.g. bilateral MCA occlusions, or an MCA and a basilar artery occlusion)