title: Large middle cerebral artery infarctions and the hyperdense middle cerebral artery sign in patients with atrial fibrillation.
abstract: OBJECTIVE
  Strokes in patients with atrial fibrillation are often due to large middle cerebral artery (MCA) infarctions, caused by cardiogenic emboli. The purpose of this study was to characterise the large MCA infarctions and to describe the prevalence and prognostic value of the hyperdense middle cerebral artery sign (HMCAS) in patients with atrial fibrillation.
  
  
  METHODS
  The patient material comprised all 449 patients included in a randomised clinical trial of low molecular-weight heparin versus aspirin in patients with acute ischaemic stroke and atrial fibrillation. Patients with Scandinavian Stroke Scale score <8 were excluded. CT was performed on admission and at day 7, and was evaluated blinded to clinical data. The CT findings on admission were related to functional outcome at 14 days and 3 months, and incidence of cerebral haemorrhage within 7 days.
  
  
  RESULTS
  Altogether 66/449 (15%) of the patients had large MCA infarctions. These patients had poorer clinical outcomes, and a higher frequency of haemorrhage on control CT within 7 days (15/59, 26% vs. 43/368, 12%). The HMCAS was found in 32/449 (7%) of the patients. It was significantly more frequent in patients with large MCA infarctions (17/66, 26% vs. 15/383, 4%), and was found most frequently within the first few hours following stroke onset. The HMCAS was associated with poor clinical outcomes and a higher frequency of cerebral haemorrhage, but these effects were partially explained by a preponderance of other risk factors in the HMCAS group.
  
  
  CONCLUSIONS
  Large MCA infarction is a frequent finding in patients with atrial fibrillation. These patients have a high prevalence of the HMCAS, which is an early infarction sign and a marker of a poor prognosis.
authors.affiliation: Department of Haematology, Haematological Research Laboratory, and Department of Neuroradiology, Ullevål University Hospital, Oslo, Norway.
authors.forename: E
authors.initials: E
authors.lastname: Berge
authors.forename: P H
authors.initials: PH
authors.lastname: Nakstad
authors.forename: P M
authors.initials: PM
authors.lastname: Sandset
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000150:complications*; D005260:Female; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000209:etiology; D020766:Intracranial Embolism / Q000000981:diagnostic imaging / Q000209:etiology; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging*; D011379:Prognosis; D016032:Randomized Controlled Trials as Topic; D013997:Time Factors; D014057:Tomography, X-Ray Computed