Outcomes/Effectiveness Research

A certain type of stroke increases risk of death and poor outcome

Acute ischemic stroke is caused when a blood clot blocks an artery in the brain. Several large vessels in the brain can be affected. When they become blocked during a stroke, it is called a large vessel occlusion (LVO). A new study, using various brain imaging techniques, has found that LVO accounts for nearly half of all acute ischemic strokes. In addition, having this type of stroke increases the odds of dying and decreases the odds of having a good clinical outcome.

The researchers collected clinical and 6-month outcome data on 735 patients with suspected acute stroke at 2 academic medical centers. All patients underwent imaging studies to determine if they indeed had a stroke, its type, and clinical features. A total of 578 were verified as having a stroke; 97 experienced a transient ischemic attack (TIA, a temporary, minor blood flow stoppage that is not considered a stroke).

An LVO accounted for 46 percent of all patients with stroke and 13 percent of patients with TIA. Compared with patients who had suffered small vessel occlusions, those with LVO had significantly higher (poorer) stroke scores resulting from a 7.8 increase in scoring. Having an LVO was also associated with 4.5-fold increased odds of death compared with patients with normal imaging findings. Stroke patients without an LVO had threefold greater odds of having a good outcome compared with patients with LVO. An LVO involving the basilar artery in the brain was associated with the worst outcome and highest mortality. The study was supported in part by the Agency for Healthcare Research and Quality (HS11392).

See "Significance of large vessel intracranial occlusion causing acute ischemic stroke and TIA," by Wade S. Smith, M.D., Ph.D., Michael H. Lev, M.D., F.A.H.A., Joey D. English, M.D., Ph.D., and others in the December 2009 Stroke 40, pp. 3834-3840.

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