TUESDAY, Sept. 9 (HealthDay News) -- It's safe to give the clot-dissolving drug tPA to people with very high blood pressure after they have suffered a stroke, a new study indicates.

The American Heart Association recently updated its stroke treatment guidelines to recommend use of tPA, tissue plasminogen activator, in such cases, "but there was no evidence to support that," said study leader Dr. Sean I. Savitz, co-director of the stroke center at the University of Texas Medical School at Houston. "This is the first evidence," Savitz said.

The study cited a previous report that perhaps 10 percent of people eligible for tPA treatment after a stroke don't get it because of fear that the medication might cause excess bleeding. About 30 percent of people who have strokes have very high blood pressure, defined as 180/110 or higher, Savitz said.

Savitz and his colleagues, including Dr. Sheryl Martin-Schild, now at Tulane University Health Sciences Center, reviewed the medical records of 178 people who had ischemic strokes -- the most common kind, in which a blood clot blocks a brain artery -- and who got intravenous tPA within three hours, the recommended time frame.

Fifty of them had blood pressure high enough to require medication, the researchers said. Their strokes tended to be more severe, and they had higher blood sugar levels, a bad indicator for outcomes. They were given intravenous drugs such as beta blockers and calcium channel blockers to lower blood pressure even as they received the clot-dissolving therapy.

The study was done "to find out the safety of aggressively treating patients with high blood pressure and stroke," Savitz said. "We finally know it's OK, because the bleeding rates were not different, and the outcome rates were not different" in those who did or did not get blood pressure treatment.

The findings were published in the September issue of the journal Archives of Neurology.

Savitz said the study goes part of the way in settling an issue that arose in the 1990s, when tPA was shown to be effective in the first hours after a stroke. But more trials are needed on the treatment of high blood pressure in the hours after a stroke, he said.

"How aggressive should you be in doing it?" he said. "If you lower it too much, you can do damage, because the brain depends on blood pressure to supply it with blood."

Dr. Irene Katzan, a vascular neurologist at the Cleveland Clinic, called the new findings "very intriguing," but she added, "I don't think the data are enough to warrant a change in practice."

At the Cleveland Clinic, the practice is to try to bring down elevated blood pressure, but not usually as aggressively as done in the Texas study, she said.

"The guidelines are straightforward in regard to blood pressure control," Katzan said. "We follow what is recommended for a blood pressure of 185 over 110. Some medication is fine, but aggressive use of blood pressure medication poses something of a contraindication to therapy."

But the Texas report could herald a change in treatment, Katzan said. The Houston group is foremost in stroke treatment and, Katzan added, "I think that other future reports that are similar to this could be used potentially to alter practice," she said.

More information

Learn more about the use of tPA in stroke patients from the American Heart Association .