Inclusion criteria
Age greater than 18 years
Clinical diagnosis of ischemic stroke, with onset of symptoms within three hours of initiation of treatment
Noncontrast CT scan with no evidence of hemorrhage
Exclusion criteria
History
	Stroke or head trauma in previous three months
	History of intracranial hemorrhage that may increase risk of recurrent hemorrhage
	Major surgery or other serious trauma in previous 14 days
	Gastrointestinal or genitourinary bleeding in previous 21 days
	Arterial puncture in previous seven days
	Pregnant or lactating patient
Clinical findings
	Rapidly improving stroke symptoms
	Seizure at onset of stroke
	Symptoms suggestive of subarachnoid hemorrhage, even if CT scan is normal
	Persistent systolic pressure greater than 185 mm Hg or diastolic pressure greater than 110 mm Hg, or patient is requiring aggressive therapy to control blood pressure
	Clinical presentation consistent with acute myocardial infarction or postmyocardial infarction pericarditis requires cardiologic evaluation before treatment
Imaging results
	CT scan with evidence of hemorrhage
	CT scan with evidence of hypodensity and/or effacement of cerebral sulci in more than one third of middle cerebral artery territory
Laboratory findings
	Glucose level less than 50 mg per dL (2.8 mmol per L) or greater than 400 mg per dL (22.2 mmol per L)
	Platelet count less than 100,000 per mm3 (100 × 109 per L)
	Patient is taking warfarin and has abnormal International Normalized Ratio
	Patient has received heparin within 48 hours, and partial thromboplastin time is elevated