Importance Limited data exist regarding the natural history of proximal intracranial arterial occlusions.
Objective To investigate the outcomes of patients who had an acute ischemic stroke attributed to an anterior circulation proximal intracranial arterial occlusion.
Design, Setting, and Participants A prospective cohort study at 2 university-based hospitals from 2003 to 2005 in which nonenhanced computed tomography scans and computed tomography angiograms were obtained at admission of all adult patients suspected of having an ischemic stroke in the first 24 hours of symptom onset.
Exposure Anterior circulation proximal intracranial arterial occlusion.
Main Outcomes and Measures Frequency of good outcome (defined as a modified Rankin Scale score of ≤2) and mortality at 6 months.
Results A total of 126 patients with a unilateral complete occlusion of the intracranial internal carotid artery (ICA; 26 patients: median National Institutes of Health Stroke Scale [NIHSS] score, 11 [interquartile range, 5-17]), of the M1 segment of the middle cerebral artery (MCA; 52 patients: median NIHSS score, 13 [interquartile range, 6-16]), or of the M2 segment of the MCA (48 patients: median NIHSS score, 7 [interquartile range, 4-15]) were included. Of these 3 groups of patients, 10 (38.5%), 20 (38.5%), and 26 (54.2%) with ICA, MCA-M1, and MCA-M2 occlusions, respectively, achieved a modified Rankin Scale score of 2 or less, and 6 (23.1%), 12 (23.1%), and 10 (20.8%) were dead at 6 months. Worse outcomes were seen in patients with a baseline NIHSS score of 10 or higher, with a modified Rankin Scale score of 2 or less achieved in only 7.1% (1 of 14), 23.5% (8 of 34), and 22.7% (5 of 22) of patients and mortality rates of 35.7% (5 of 14), 32.4% (11 of 34), and 40.9% (9 of 22) among patients with ICA, MCA-M1, and MCA-M2 occlusions, respectively. Age (odds ratio, 0.94 [95% CI, 0.91-0.98]), NIHSS score (odds ratio, 0.73 [95% CI, 0.64-0.83]), and strength of leptomeningeal collaterals (odds ratio, 2.37 [95% CI, 1.08-5.20]) were independently associated with outcome, whereas the level of proximal intracranial arterial occlusion (ICA vs MCA-M1 vs MCA-M2) was not.
Conclusions and Relevance The natural history of proximal intracranial arterial occlusion is variable, with poor outcomes overall. Stroke severity and collateral flow appear to be more important than the level of proximal intracranial arterial occlusion in determining outcomes. Our results provide useful data for proper patient selection and sample size calculations in the design of new clinical trials aimed at recanalization therapies.
A proximal intracranial arterial occlusion is an independent factor associated with poor functional outcomes and high mortality rates in patients with acute ischemic stroke.1- 3 Yet limited data exist about the natural history of proximal intracranial arterial occlusions. Most of the available information about the course of this disease comes from large intervention trials that might have limitations (such as limited generalizability) owing to their intrinsic design.1,2
Currently, the only approved pharmacological therapy for the treatment of acute ischemic stroke is intravenous (IV) tissue plasminogen activator (tPA) administered within 4.5 hours of symptom onset. Intra-arterial techniques, including mechanical thrombectomy, are rapidly evolving and may represent an option for those patients who have contraindications to IV tPA or for those patients for whom IV tPA is not effective. However, its efficacy remains to be proved in randomized trials. Further information on the natural history of proximal intracranial arterial occlusions is essential for the proper design of clinical trials to test the efficacy of endovascular approaches. In the present study, we sought to establish the rates and predictors of long-term outcomes of patients who had an acute ischemic stroke attributed to an anterior circulation proximal intracranial arterial occlusion and who did not undergo any reperfusion therapy.
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