Long-term clinical outcome after extracranial–intracranial bypass surgery for atherosclerotic vessel occlusion in patients with diminished cerebrovascular reserve capacity and recurrent ischaemic events despite medical management

BACKGROUND: Controversy persists regarding flow-augmentation bypass for steno-occlusive atherosclerotic cerebrovascular disease (ACVD), especially after the divisive Carotid Occlusion Surgery Study (COSS) and Middle Cerebral Artery Occlusion Surgery Study (CMOSS) trials. High complication rates (COSS) and the selection of patients with stable disease under conservative management (CMOSS) yielded conflicting results. Despite conflicting evidence, some authors argue for the procedure's continued relevance, supported by reduced perioperative complication rates and a distinct contemporary patient cohort. This study contributes to the ongoing discourse by presenting our centre's experience. METHODS: We analysed data (2007-2023) from our extracranial-intracranial bypass registry. Included were patients with ACVD, reduced cerebrovascular reserve and recurrent minor strokes/transient ischaemic attacks (TIAs) or progressive stroke despite maximal conservative therapy. RESULTS: A total of 98 procedures were performed in 89 patients (mean age 61 years, median follow-up 27.4 months). Internal carotid artery (ICA) occlusion was most common (88.8%), with 27.6% showing additional intracranial stenoses. Isolated middle cerebral artery (MCA) and anterior cerebral artery (ACA) stenosis were rare. Presentations included single TIA (14.3%), multiple TIAs (44.9%), recurrent strokes (26.5%) and progressive stroke (14.3%). Preoperatively, 62.2% had unilateral and 37.8% bilateral cerebrovascular reserve capacity impairment. ICA stenosis with additional intracranial disease was more often linked to bilateral impairment. Postoperative bypass patency was 96.9% at 30 days; perioperative stroke occurred in 4.1%. Long-term patency was 96.3%, with 3.7% experiencing recurrent TIAs. CONCLUSION: Flow-augmentation bypass remains a valuable option in carefully selected ACVD patients with progressive disease, offering low perioperative risk and reduced stroke recurrence.