Patients Receiving Extracranial to Intracranial Bypass for Atherosclerotic Vessel Occlusion Today Differ Significantly From the COSS Population

Despite the findings reported in the COSS (Carotid Occlusion Surgery Study), patients with atherosclerotic cerebrovascular disease continue to be referred for superficial temporal artery to middle cerebral artery bypass surgery. Here, we determined how today’s patients differ from the population reported in COSS.We retrospectively analyzed all patients that were referred to our Department for superficial temporal artery to middle cerebral artery bypass surgery of atherosclerotic cerebrovascular disease following the publication of COSS.Between 2012 and 2019, 179 patients were referred for 186 bypass surgeries. Ninety-one (51%) patients suffered atherosclerotic, unilateral internal carotid occlusion and 88 (49%) atherosclerotic multivessel disease. All patients had received intensive medical management. A single transitory ischemic attack or ischemic stroke within the last 120 days according to the inclusion criteria of COSS occurred in only 36 out of 179 (20%) patients, whereas 27 out of 179 (15%) suffered >1 transitory ischemic attack within 120 days, 109 out of 179 (61%) had recurrent minor ischemic stroke, and 7 out of 179 (4%) were hemodynamically unstable and required blood pressure maintenance. The distribution of symptoms did not differ between atherosclerotic unilateral internal carotid artery occlusion and atherosclerotic multivessel disease (P=0.376) but hemodynamic impairment was significantly greater in atherosclerotic multivessel disease (P<0.001 for atherosclerotic multivessel disease versus atherosclerotic unilateral internal carotid artery occlusion). The overall perioperative stroke rate was 4.3%.Patients referred for flow augmentation surgery today appear to suffer more severe symptoms and vessel occlusion patterns than patients reported in COSS. A new, carefully designed randomized controlled trial appears warranted, considering the still poor prognosis of severe atherosclerotic cerebrovascular disease.