In the current study, investigators used the large Registry of the Canadian Stroke Network (RCSN) to compare the outcomes of 1,562 ischemic stroke patients treated at the 11 stroke centers in Ontario between 2003 and 2008. Fifty-one percent were male (average age 72) and 49 percent female (average age 75). Risk factors and the severity of initial symptoms were similar in the 1,082 patients (69 percent) witnessed having a stroke and the 480 (31 percent) treated based on "time last seen normal." Patients with unwitnessed strokes were more likely to be treated greater than 3 hours after "time last seen normal" (27 vs. 12.1 percent).

"If anything, patients identified at the time last seen normal are better candidates for tPA than those in the ECASS trial, which enrolled only those witnessed having a stroke," said Sahlas, who practices at the Central South Ontario Regional Stroke Centre at Hamilton Health Sciences.

Patients in the registry included many who would have been excluded from the ECASS-3 trial because they were over 80 years of age or had previous strokes or diabetes.

"This study provides added justification for extending the window and taking all comers - not just those witnessed having their strokes," Sahlas said.

"If you come across someone who has had a stroke, act quickly. Be aware that 'time is brain' and seek immediate medical attention. If you last saw someone normal an hour or two ago, that doesn't necessarily disqualify them from receiving tPA."

Researchers who conducted the retrospective study said further prospective research is needed, particularly within the extended time window, to determine whether a difference in clinical outcome is observed.

Source: American Heart Association