Doctors now have an additional 90 minutes in which to treat and try to limit the damage from acute strokes with the most commonly used therapy, the clot-busting agent known as tPA.
A recent science advisory from the American Heart Association and American Stroke Association recommends extending the time window for treatment with the use of tPA intravenously to between three and 4 1/2 hours after symptoms occur.
In an acute ischemic stroke, the formal name of the attack in the brain, a blood clot blocks a vessel, causing tissue damage that can result in permanent disability or even death. The clot needs to be quickly broken up, restoring blood flow to the area.
Previously the use of tPA could be given only within the three hours after onset of acute stroke symptoms, a time constraint that local experts said was based on a relatively small study of only 600 patients completed in 1995.
"The concern was if you waited too long in giving tPA, the chance of significant bleeding in the brain would be too great and offset the benefits. The benefits also would be less the longer you waited," said Dr. Lawrence Wechsler, director of the Stroke Institute of the University of Pittsburgh Medical Center.
Subsequently, a larger trial overseas called the European Cooperative Acute Stroke Study 3, published in September 2008 in the New England Journal of Medicine, showed otherwise.
Since then, "when the decision is up to us, we have extended the window to 41/2 hours," said Dr. Wechsler. "Three or four" have been done in that window and, he said, "they've done as we expected ... similarly to our experiences with patients under three hours."
Dr. Ashis Tayal, medical director of the Comprehensive Stroke Center at Allegheny General Hospital, said the North Side facility had yet to use tPA in the extended window but was prepared to do so.
The heart and stroke associations' new advisory also is based primarily on the findings of that European study.
Both Pittsburgh experts joined the national associations in stressing that the new guidelines do not mean physicians can hesitate before deciding to start tPA therapy.
"The important message is [that] it's not suggesting that people have more time and can slow down in evaluating the patient," Dr. Tayal said. "Giving the drug earlier benefits the patient more, and patients should be treated with the same sense of urgency whether they arrive less than three hours from onset or beyond three hours. ...
"Patients should be evaluated with the goal of beginning treatment within an hour of their arrival" at a hospital, he added.
The new AMA/ASA advisory does include some exceptions. Categories of patients not included in this recommendation for receiving tPA beyond three hours of stroke onset include those older than 80; those taking oral anticoagulants like Coumadin; victims of severe stroke; and those with a combined medical history of stroke and diabetes.
AGH, UPMC Presbyterian-Shadyside and UPMC Mercy -- all designated as primary stroke centers by the Joint Commission -- offer these catheter-delivered therapies, Dr. Tayal and Dr. Wechsler said.
Pohla Smith can be reached email@example.com or 412-263-1228.