March 9, 1999
Web posted at: 5:40 p.m. EST (2240 GMT)

From Medical Correspondent Rhonda Rowland

NEW ORLEANS (CNN) - An experimental treatment to bypass clogged arteries in the heart by growing new ones has yielded disappointing results, researchers said Tuesday.

The treatment, known as angiogenesis, works by growing new, tiny blood vessels to bypass the coronary arteries, which supply blood to heart muscle.

The first large study of the therapy, released at this week's American College of Cardiology conference in New Orleans, shows all patients involved in the tests improved. But the improvements came whether they received angiogenesis or no treatment at all.

All of the patients did better on a treadmill test, but there's no evidence that angiogenesis improved heart function. The study did show, however, that the treatment is safe.

Researchers used a compound known as VEGF to trigger the growth of new blood vessels.

"In the patients that were treated with VEGF, there were no bad, adverse outcomes," said Dr. Timothy Henry of Hennepin County Medical Center in Minneapolis. "In this area of growth factor therapy, people have been worried about (whether) these growth factors cause cancer, (or) can they cause abnormal blood vessel growth in your eyes, for example."

Angiogenesis is one of the hottest and most controversial fields in cardiology, and the study comes after several years of hype and expectations. Genentech Inc., the company that developed VEGF and paid for the study, says it is disappointed the patients did not do better.

But researchers say they're not discouraged by the less-than-glowing study results of the treatment: They say this is part of the scientific process, and many agree the idea of growing new blood vessels in the heart has a future.

"People have asked me will this change your excitement for the field and my answer to that is no," Henry said. "I'm very excited in this area, and I think the enthusiasm here is real."

Angiogenesis pioneer Dr. Jeffrey Isner shares Henry's enthusiasm. But Isner, a researcher at Tufts University in Boston, is using a slightly different technique - one in which a gene is injected directly into the heart.

Isner says he's had 24 patients undergo the procedure, and all have improved.

"This theoretical difference between these two techniques has been the subject of a lot of controversy and a lot of debate, and all of us have suggested that we simply need clinical trials of both," Isner said.