The Mechanism of Procedural Stroke Following Carotid Endarterectomy within the Asymptomatic Carotid Surgery Trial 1.

INTRODUCTION: Understanding the pathophysiological mechanism of procedural stroke during carotid intervention may help reduce the risk of stroke in those undergoing surgery. We therefore studied the features of procedural strokes within the first Asymptomatic Carotid Surgery Trial-1 (ACST-1) to identify the underlying pathophysiological mechanism. METHODS: In ACST-1, 3,120 patients with severe asymptomatic carotid stenosis thought suitable for surgery were randomized to CEA or indefinite deferral of surgery. Information on procedural (within 30 days) stroke type, laterality, severity and timing was collected. Eight possible mechanisms were defined: embolism from the carotid artery, haemodynamic, thrombosis or occlusion of the carotid artery, hyperperfusion syndrome, cardioembolic, either carotid embolic or haemodynamic, either carotid embolic or thrombotic occlusion, or undetermined. RESULTS: Procedural strokes occurred in 53 patients (2.7%). Strokes were predominantly ischaemic (n = 43; 81%), ipsilateral to the treated artery (n = 42; 79%), often occurred on the day of the operation (n = 32; 60%) and in over half the patients, were disabling or fatal (n = 27; 51%). The identified stroke mechanism was carotid embolic (n = 7), haemodynamic (n = 5), thrombosis or occlusion of the carotid artery (n = 9), hyperperfusion (n = 7), cardioembolic (n = 3), 'probably carotid embolic or haemodynamic' (n = 7), 'probably carotid embolic or thrombotic occlusion' (n = 3) and undetermined in 12 cases. CONCLUSION: In ACST-1, the risk of procedural stroke was low. Most strokes (60%) occurred on the day of the procedure and were caused by thrombosis or thrombotic occlusion of the ipsilateral carotid artery. These findings emphasize the importance of immediate assessment of the treated carotid artery when a stroke occurs after CEA.