Tirofiban for Patients Treated With Alteplase

Inclusion Criteria: * Age ≥18 * Ischemic stroke symptom with onset ≤4.5 hours treated with IV rt-PA according with local guidelines. * 6≤ NIHSS ≤20 before IV tPA, or NIHSS \>20 but decrease ≥ 8 after IV rt-PA. * ≥ 4 point total NIHSS or ≥ 2 point in one NIHSS category during and after the IV rt-PA compared to immediately before worsening, an emergency CT scan should be performed to exclude intracranial hemorrhage * Patients or their legally acceptable representative agreed to the treatment and signed the informed consent form Exclusion Criteria: * Patients whom the treating physician is planning to treat with mechanical thrombectomy or other endovascular procedure (e.g. Intra-arterial thrombolysis) according with local guidelines. * Patients had used antiplatelet therapy in the past 5 days before the stroke. * Patients had used anticoagulant therapy in the past 5 days before the stroke. * Scheduled for surgery or interventional treatment requiring study drug cessation. * CT scan finding of hypoattenuation involving ≥1/3 of the MCA territory. * Any evidence of clinically significant bleeding ,or known coagulopathy. * Renal insufficiency (creatinine clearance rate \<30ml/min) * Hepatic dysfunction (ALT \>2 folds of Upper limit of normal value or AST\>2 folds of Upper limit of normal value). * Pre-existing disability with ≥ mRS 2. * Known allergic to tirofiban or other glycoprotein IIb/IIIa antagonist. * Severe non-cerebrovascular disease with life expectancy \<3 months