Two Cases of Delayed Severe Stenosis after Complete Recanalization by Mechanical Thrombectomy.

Objective: Mechanical thrombectomy is constantly advancing in terms of devices and techniques to enhance outcomes, and it is now commonly performed worldwide. Delayed stenosis is a potential complication that can occur following the procedure. However, its pathophysiology, risk factors, and time of onset remain unclear. We report 2 cases of delayed severe stenosis after mechanical thrombectomy. Case Presentation: Case 1: A 70-year-old man was referred to our hospital with a right middle cerebral artery occlusion. We performed mechanical thrombectomy promptly. Complete recanalization was achieved after the 2nd thrombectomy attempt with no complications. Case 2: A 24-year-old man was sent to our hospital with an occlusion in his left middle cerebral artery. We quickly performed mechanical thrombectomy, successfully achieving recanalization after the 6th attempt. A post-procedural CT scan revealed an intracranial hemorrhage. In both cases, although no stenosis was observed the next day, significant delayed stenosis was discovered months later after mechanical thrombectomy. However, the patients remained asymptomatic. Conclusion: Mechanical thrombectomy is a recognized treatment for acute ischemic stroke, but there are instances of delayed stenosis following the procedure. Excessive vessel injury caused due to thrombectomy may lead to delayed stenosis. This report emphasizes the importance of regular follow-up after mechanical thrombectomy, particularly in cases where there is a potential for substantial vascular damage due to thrombectomy.