Excessive accumulation or abnormal distribution of adipose tissue is a recognized risk factor for ischemic stroke. However, the impact of overweight or obesity on clinical outcomes of ischemic stroke is uncertain. The proposition of obesity paradox in stroke patients makes secondary prevention ambiguous for patients with ischemic stroke and overweight or obesity. Body mass index (BMI) or abdominal visceral fat area was used to measure obesity in previous studies. Epicardial adipose tissue (EAT) is a unique visceral fat, which has higher expression of proinflammatory genes than subcutaneous fat and abdominal visceral fat. And inflammation is closely related to the prognosis of ischemic stroke. In this study, the investigators assume EAT volume or attenuation evaluated by chest computed tomography (CT) scan might affect the prognosis of patients with acute ischemic stroke (AIS). Patients with the first acute ischemic stroke will be stratified into tertile groups based on EAT volume or attenuation. The primary endpoint measure is the proportion of patients with a favorable recovery of nerve function deficiency assessed by Modified Rankin Scale （mRS≤2） at 90 days after the onset of symptoms. Secondary endpoints include the following: the percentage of functional recovery measured by the Barthel Index (BI) at day 90 after stroke onset, the propotion of clinical improvement (with an improvement of ≥ 4 points on the National Institute of Health Stroke Scale score or the resolution of the neurologic deficit) or neurological deterioration (with a decline by ≥ 4 points in the total National Institute of Health Stroke Scale score) at day 7 after stroke onset, incidence of hemorrhagic transformation and mortality within 7 days of symptom onset.

Inclusion Criteria:

• Patient is between 18 and 80 years of old;
• Acute ischemic stroke（AIS）is diagnosed by brain imaging, and this is the first ischemic stroke event;
• Patient is admitted to hospital within 72 hours after stroke onset;
• Modified Rankin scale score (mRS) ≤2 before onset;
• Patient undergoes chest CT scanning during hospitalization;
• Provision of written informed consent.

Exclusion Criteria:

• Pregnant or nursing women;
• Complicated with cerebral hemorrhage showed by cranial CT on admission;
• Patient had brain tumor, intracranial aneurysm, arteriovenous malformation, or cerebral hemorrhage or underwent brain surgery in the past;
• Severe cardiac, liver, pulmonary, or kidney disease, malignancy, severe coagulation dysfunction, and systemic organ dysfunction;
• Failure to accomplish 7-day and 3-month follow up.

This study intends to recruit 200 patients with the first acute ischemic stroke. They undergo chest CT scanning during hospitalization to evaluate epicardial adipose tissue volume and attenuation.