Long‐Term Stability of Patients Undergoing Endovascular Parent Artery Occlusion of Their Intracranial Artery

Background Although endovascular parent artery occlusion (PAO) of the intracranial artery is a well‐established treatment option, the long‐term stability of cerebral blood flow remains a concern. This study aimed to evaluate the long‐term clinical and radiological outcomes of patients who underwent PAO. Methods The patients who underwent endovascular PAO of their internal carotid or vertebral artery (VA) between April 2011 and March 2022 were included in this observational study. Information about patient characteristics, details of the endovascular treatment, and clinical and radiological follow‐up were collected. Results The study included a total of 104 cases (average age, 52.9±12.6 years old; men, 73 [70.2%] cases; 95 [91.3%] VA PAO cases) from 8 centers. Most cases were performed in an emergency condition, such as ruptured VA dissecting aneurysm (73 cases [70.2%]). PAO was successful in all cases. Early stroke (within 30 days) occurred in 33 (31.7%) cases (31 cases in VA PAO and 2 cases in internal carotid PAO) with ischemic stroke (29 cases) comprising the largest group. Clinical follow‐up over 1 month was available in 85 cases. During an average follow‐up period of 45.8±25.8 months, 1 case of VA PAO experienced a stroke without functional deterioration. Imaging follow‐up was performed in 75 cases. Recanalization of the occluded VA was observed in 2 cases. The remaining image change was contralateral VA stenosis after VA PAO. The incidence of clinical and radiological events was 1.2% and 1.1% per patient‐year, respectively. Conclusion Once the patients surpass the acute phase after PAO, their mid‐ to long‐term course was stable. The risk of late stroke or de novo aneurysm formation was lower than expected in the literature, and the direct comparison to novel reconstructive techniques is warranted in future studies. Clinical Trial Registration information: https://www.umin.ac.jp/ctr/index.html, trial ID: UMIN000045160