Stroke victims selected by CT for treatment fared better even after 3 hours

Stroke patients who were selected by perfusion CT for intravenous thrombolytic treatment more than three hours after symptoms occurred had favorable outcomes, according to a literature review published online on Sept. 19 in Radiology.

Lead researcher Kirsteen R. Burton, MBA, MSc, MD, of the University of Toronto, and colleagues conducted a systematic review and meta-analysis of stroke patients who underwent imaging and treatment to determine rates of death, disability and symptomatic intracranial hemorrhage (SICH) among patients with acute ischemic stroke.

Among patients who received intravenous thrombolytic treatment after perfusion CT, the mortality rate was higher at 12.5 percent for patients treated within three hours of symptoms onset, compared with the mortality rate of 2.9 percent for patients treated more than three hours after symptom onset. The SICH rate was 3.3 percent for the patients who received treatment sooner, and 3.9 percent for those who received it later.

There are several factors that could have contributed to the study’s “paradoxical” findings, commented Burton and colleagues. “Outcomes of patients with acute ischemic stroke (AIS) may be influenced by many factors, including patient age and stroke severity at presentation.” However, because of differences in the way patient ages were reported, researchers were unable to test the significance of differences in patient ages between the two time groups, the authors wrote.

The mean patient ages (69–71 years), however, appeared similar in each of the studies included, except for one in which the mean age was 58.7 years for patients treated within three hours.

Stroke severity at presentation could also have influenced the study’s findings, as well as the inclusion of two studies of middle cerebral artery territory severe strokes, they wrote.

Researchers conducted a search of the literature from 1946 up to July 2012 using the databases of MEDLINE, EMBASE, the Cochrane Library and PubMed. They also searched Google Scholar on terms including “brain ischemia” and “perfusion imaging.” The search was unrestricted by language of publication. Two reviewers extracted study data and independently assessed the risk of study bias. Outcomes of patients selected by using perfusion CT, including case-fatality rate, favorable outcome (modified Rankin Scale [mRS] score, ≤2), and rates of SICH, were estimated.

The 13 studies included in the analysis were published between 2000 and 2012, with seven published in 2011 or 2012.