Death from ischemic stroke in the anterior circulation: the contralateral carotid matters.

Death from acute hemispheric infarction is commonly associated with stroke size, but the potential role of the internal carotid artery (ICA) in this phenomenon is poorly understood. The aim of the present study was to analyse the relation between the degree of ipsilateral and contralateral ICA stenosis, infarct type and death. We studied 2,148 first-ever stroke patients with anterior circulation infarction from the Lausanne Stroke Registry. Doppler ultrasonography with frequency spectral analysis and Duplex-scanning were performed systematically during the acute phase of stroke. The patients were divided into groups according to the degree of ipsilateral and contralateral ICA stenosis. The case fatality ratios (CFR) at hospital discharge were obtained for each group. Several clinical features including age, stroke topography, level of consciousness, limb weakness on admission, type of onset, hyperglycemia, previous transient ischemic attack, cardiac ischemia, cardiac arrhythmia and left ventricular hypertrophy were also studied. Mortality increased significantly with ipsilateral ICA stenosis: </=50% stenosis, 2.8%, (44/1,549); >50% and </=90% stenosis, 3.5%, (6/170); >90% stenosis, 5.6%, (24/429); p = 0.026, but not significantly with contralateral ICA stenosis. However, patients without ipsilateral ICA stenosis had significantly higher mortality when contralateral stenosis was present: 16.7% (3/18) versus 2.7% (41/1,531), p = 0.013. This corresponded to an increased frequency of strokes involving the whole middle cerebral artery territory, with impaired consciousness at onset of stroke. Patients with ipsilateral stenosis had similar CFR independently of the presence or absence of contralateral stenosis. In conclusion, patency of the contralateral ICA may be an important contributory factor of larger infarction and indirectly of stroke mortality in patients with no ipsilateral stenosis.