Clot-Preventing Drug Improves Heart Blood Flow After Angioplasty

But doctors question whether the practice results in long-term benefits

THURSDAY, May 3, 2007 (HealthDay News) -- Infusing the clot-preventing drug streptokinase improved blood flow in the tiniest heart blood vessels of people who had artery-opening procedures such as angioplasty, a small Turkish study found.

It's an intriguing study, cardiologists in other countries said, but there's a real question about whether that improvement does any good over the long run.

"We've done this kind of work in the past," said Dr. Kirk Garratt, clinical director of interventional cardiovascular research at Lenox Hill Hospital in New York City. "Giving this drug and drugs like this to improve outcome, it never worked."

But, Garratt added, there are some important differences in what the cardiologists at Istanbul University reported in the May 3 issue of the New England Journal of Medicine. One is that general treatment of people undergoing artery-opening procedures has improved in recent years. The patients in the Turkish trial who were given streptokinase were also given other clot-preventing drugs such as Plavix, for example.

Most significant, the Turkish doctors did extensive measurements of microvascular function -- blood flow through the smallest heart vessels. They found that it was much better than in trial participants who did not get streptokinase.

That was a different result from previous research, Garratt said. "Then, we were looking at how the heart pumped blood," he said. "We didn't find a difference."

That was ultimately true in the Turkish study. After six months, "there was no evidence of a difference between the two study groups in left ventricular size or function," the researchers wrote, referring to the blood-pumping chamber of the heart.

"If you're interested in microvascular flow as an endpoint, this is an approach worth pursuing," Garratt said. "There is some evidence that improving microvascular flow improves outcome."

But even then, streptokinase may not be the best clot-preventing drug to use, Garratt said. "It has probably the worst bleeding rate out there," he said. "When we did this before, we saw lots of bleeding, and that is a significant limitation. Even if you show that improved microvascular flow is beneficial in the long term, bleeding is a problem."

The Turkish study also was a very small study, noted Dr. Jan J. Piek, professor of cardiology at the Academic Medical Center in Amsterdam, the Netherlands, who wrote an accompanying editorial in the journal. "We have to be a little bit careful, because they studied only 41 patients," he said. "I would consider it a hypothesis-generating study that has to be tested in a larger randomized trial."

Participants in such a trial would have to be chosen carefully, Piek said. "I would focus more on the uniform selection of patients," he said.

"Those who would benefit most would be patients with large myocardial infarctions [heart attacks]. They would be the most appropriate on whom to test this technique," Piek suggested. "The trial would have to be done in a sensitive setting, including only patients with larger infarcts, rather than the non-uniform selection of patients for this trial," he added.

More information

Learn more about angioplasty from the U.S. National Library of Medicine.

SOURCES: Kirk Garratt, M.D., clinical director of interventional cardiovascular research, Lenox Hill Hospital, New York City; Jan J. Piek, M.D., professor of cardiology, Academic Medical Center, Amsterdam, the Netherlands; May 3, 2007, New England Journal of Medicine
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