ORLANDO, Fla. (AP) - Doctors can boost the heart's pumping power after a heart attack by injecting bone marrow scavenged from the victim's own hip, the most rigorous test yet of the technique has shown.
The idea, called cell therapy, is intended to strengthen the heart by reseeding it with cells taken from elsewhere in the patient's body. Just how it works is a mystery, but in theory the new cells transform themselves into muscle or blood vessels or encourage the heart to repair itself.
Several small studies in recent years have yielded promising results, suggesting that patients seem to do better after the treatments. But the latest experiment, released Monday, is the first to put this to a rigorous comparison test.
German doctors who did the experiment said the results are encouraging, and they are planning a larger test that will involve hundreds of patients. But skeptics caution much more study is necessary to show the approach is safe and effective, and it is still probably years away from routine use.
"We may be entering into a new era of heart therapy, not just preserving existing heart muscle but regenerating heart muscle with stem cells," said Dr. Helmut Drexler, chief of the cardiovascular division at Hannover Medical School.
Drexler and Dr. Kai Wollert presented the results on 60 patients at the annual scientific meeting of the American Heart Association in Orlando.
Several variations of cell therapy are in development for heart disease. Some, such as the Hannover group's, are intended to minimize damage in the first days after a heart attack. Others are aimed at strengthening hearts that have been severely weakened over the years by congestive heart failure.
Some experimenters carry in marrow stem cells or muscle cells through a catheter that is threaded into the heart's arteries, while others inject the cells into the heart during bypass surgery. Whatever the delivery method or source, all are intended to repair the heart with tissue harvested from elsewhere in the body.
"This work is so very preliminary," said Dr. Robert Bonow, cardiology chief at Northwestern University. "It is not ready for widespread clinical use, but there is great excitement."
The Hannover study randomly assigned recent heart attack patients to get the cell treatment or to be in an untreated comparison group. The results were evaluated by experts who did not know how the patients were treated.
After five to six months, doctors measured the pumping power of the patients' hearts. Those who got the cells had improved by 7 percent, compared with 1 percent among the comparison group.
"We think this stimulates the heart itself to regenerate," said Drexler.
Some earlier experiments have raised the concern that cell therapy might trigger heart rhythm problems that lead to cardiac arrest. Drexler said he saw no sign of this in his study.
However, Dr. Raymond Gibbons of the Mayo Clinic cautioned that because of the study's small size, "there could be an adverse event that occurs in one in 100 that would be entirely missed."
The first time the approach was attempted after a heart attack was March 2001 at Heinrich Hein University in Dusseldorf, Germany, where doctors treated a 46-year-old man who is still doing well. Dr. Bodo Strauer said that in all, his team has treated 20 patients, who appear to have improved when judged with a variety of measures.
If the approach proves to work, its most important use might be in restoring the damaged hearts of people with congestive heart failure, a condition that results in more than 1 million U.S. hospital admissions annually.
Dr. Nabil Dib of the Arizona Heart Institute, who has treated 18 heart failure patients, said that if the promising early results hold up, "I think this therapy will replace heart transplants" for these people.
Dr. Emerson Perin of Baylor College of Medicine has tested the approach on 11 volunteers with severe heart failure. At the start, about 15 percent of their heart muscle was found to be still alive but not getting enough blood to function. Six months after the treatment, this dropped to 9 percent.
Among his patients were five who were waiting for heart transplants. All five improved enough to be taken off the transplant list.
EDITOR'S NOTE: Medical Editor Daniel Q. Haney is a special correspondent for The Associated Press.
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