Large middle cerebral artery infarctions and the hyperdense middle cerebral artery sign in patients with atrial fibrillation

Purpose. Strokes in patients with atrial fibrillation are often due to larg e middle cerebral artery (MCA) infarctions, caused by cardiogenic emboli. T he purpose of this study was to characterise the large MCA infarctions and to describe the prevalence and prognostic value of the hyperdense middle ce rebral artery sign (HMCAS) in patients with atrial fibrillation. Material and Methods: The patient material comprised all 449 patients inclu ded in a randomised clinical trial of low molecular-weight heparin versus a spirin in patients with acute ischaemic stroke and atrial fibrillation. Pat ients with Scandinavian Stroke Scale score <8 were excluded. CT was perform ed on admission and at day 7, and was evaluated blinded to clinical data. T he CT findings on admission were related to functional outcome at 14 days a nd 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 hae morrhage on control CT within 7 days (15/59, 26% vs. 43/368, 12%). The HMCA S was found in 32/449 (7%) of the patients. It was significantly more frequ ent 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 onse t. The HMCAS was associated with poor clinical outcomes and a higher freque ncy of cerebral haemorrhage, but these effects were partially explained by a preponderance of other risk factors in the HMCAS group. Conclusion. Large MCA infarction is a frequent finding in patients with atr ial fibrillation. These patients have a high prevalence of the HMCAS, which is an early infarction sign and a marker of a poor prognosis.