Several clinical trials (e.g., TRACE-3, EXPECTS, HOPE) have successfully extended the time window for intravenous thrombolysis (IVT) from the conventional 4.5 hours up to 24 hours after symptom onset by utilizing advanced imaging selection techniques. Consequently, the 2024 Chinese guidelines for reperfusion therapy recommend IVT for patients presenting 4.5 to 24 hours after onset, based on imaging selection criteria. However, clinical practice indicates that a considerable proportion of patients exhibit suboptimal recanalization outcomes or even experience early neurological deterioration (END) despite receiving standard IVT. Previous research, such as the ASSET-IT trial, has primarily focused on patients treated within 4.5 hours of onset. For the growing population of "extended-window" (4.5-24 hours) patients receiving IVT facilitated by advances in imaging, the optimal antiplatelet strategy following thrombolysis remains an area with no high-level evidence. Therefore, this study aims to evaluate the efficacy and safety of early administration of eptifibatide following standard IVT (with tenecteplase or alteplase) in patients with acute ischemic stroke who present 4.5 to 24 hours after symptom onset. Patients who have received standard IVT but exhibit early neurological deterioration, fluctuation, or lack of significant improvement within 1 hour post-thrombolysis will be randomized 1:1 to receive either eptifibatide (a single intravenous bolus followed by a 2-hour infusion) plus standard medical therapy or standard medical therapy alone. The primary efficacy outcome is the proportion of patients achieving an excellent functional outcome (modified Rankin Scale score of 0-1) at 90 days. The primary safety outcome is the incidence of symptomatic intracranial hemorrhage within 48 hours after randomization. A total of 786 participants are planned to be enrolled to detect a 10% absolute difference in the primary outcome with 80% power.