An experimental drug now given to heart attack victims may also be an effective treatment for patients with blood clots in their lungs, Harvard researchers will report today.

Led by Dr. Samuel Z. Goldhaber '72, an assistant professor of medicine, a group of doctors at Brigham and Women's Hospital gave a drug called Tissue Plasminogen Activator (TPA) to 40 patients with blood clots in their lungs, and it quickly broke up the clots in 37 of them.

90 Percent Success

"It exceeded our best hopes," Goldhaber said. "Over 90 percent of the clots disolved within six hours."

Although TPA has been tested in several thousand heart attack victims around the world, this study represents the first time it has been given to patients with lung clots, called pulmonary embolisms.

Blood clots can cause a variety of ailments, ranging from chronic shortness of breath to heart attacks.

"We were initially afraid that this dose of TPA wouldn't do the job, because a clot that goes to the pulmonary arteries is much bigger [than one in the arteries of the heart,]" Goldhaber said.

Although it worked effectively on most lung-clot victims, TPA also caused serious internal bleeding in six percent of the patients. Goldhaber said that more, larger-scale trials would be necessary before the Food and Drug Administration would consider approving the drug for widespread use.

Goldhaber's complete study appears in today's issue of the British journal Lancet.

More than 50,000 Americans die each year from pulmonary embolisms, and another 300,000 are hospitalized annually, the researchers estimate.

Blood clots frequently form in an artery in the leg or pelvis, travel through the blood stream and get stuck in the arteries which carry blood from the heart to the lungs.

When treating victims of pulmonary embolisms, doctors usually wait for the blood clots to dissolve on their own, although they do prescribe blood-thinning drugs to prevent more clots from forming.

Another clot-dissolving drug, Urokinase, was approved by the Food and Drug Administration for experimental use in pulmonary embolism victims in 1977, but TPA seems to work more effectively, Goldhaber said.