Debris-Collecting Device Flunks Artery Test
But an improved, second-generation model still holds hope
TUESDAY, March 1, 2005 (HealthDay News) -- A device that scoops up the fatty debris released when heart attack patients have angioplasty was not effective in a major study.
The device did not seem to spare heart tissue from damage, and researchers found no difference in the incidence of heart-damaging events occurring within six months of the attack for those who had the procedure, called "distal microcirculatory protection," and those who didn't.
During balloon angioplasty, surgeons open up a closed artery using a tiny balloon. In the process, however, tiny bits of arterial debris become dislodged and can travel throughout the body, causing trouble in smaller vessels elsewhere. Cardiologists had hoped that distal protection would capture this debris before it could do harm.
Unfortunately, the device and procedure so far appears to have failed, according to the report in the March 2 issue of the Journal of the American Medical Association. Distal protection did not improve microcirculation, help restore blood flow to the damaged area or prevent further heart damage, the study found.
The study, led by researchers at Columbia University Medical Center, included 501 patients treated at 38 medical centers in seven countries within six hours of heart attack. Half underwent standard balloon angioplasty while the other half had angioplasty plus aspiration, the medical term for the removal of dislodged debris by suction.
"We did not identify clinical usefulness of distal microcirculatory protection in acute myocardial infarction [heart attack], and its routine use in patients undergoing mechanical reperfusion therapy [angioplasty] cannot be recommended," the researchers concluded.
Experts differ about the implications of the trial.
The story is not over, said co-researcher Dr. Joseph P. Carrozza, chief of interventional cardiology at Beth Israel Deaconess Hospital, in Boston.
"The device that was used in the study was a first-generation device that was first shown to be beneficial in a different group of patients, those who had disease in bypass grafts," Carrozza said. "It did not have that effect in the latest situation. But it doesn't establish that the policy of embolic protection is not effective. Other devices that use different mechanisms, such as filter devices, are being tried."
The problem is that the system used in the trial "is a very primitive, hard-to-use device," Carrozza said. Angioplasty took 20 minutes longer when the device was used because "it takes too long to get it into an artery," he explained.
A new trial of a different device intended to filter debris out of blood vessels is getting underway, and "there will be no data until a year from now," Carrozza said. The device "works like a fishing net, allowing blood to flow through the vessel and trapping material in the net," he said.
Dr. Gregg W. Stone, professor of medicine at Columbia University Medical Center in New York, and lead author of the journal report, disagrees with that assessment. It's not the device, but the belief that removing debris makes a difference at all that is at fault, he contends.
"Debris does happen and it does break off," Stone said. "But removing it is just too little and too late, because there is so much else going on in a heart attack."
"I suspect that subsequent studies with other devices will show exactly the same thing," he said. "This device performed very well during the trial. It got debris out in three-quarters of the patients. I do not personally expect that another device will perform any better."
The issue of debris after angioplasty remains a problem that needs to be solved, however, Carrozza added.
"More and more patients today who have heart attacks are treated with angioplasty and stenting [insertion of a flexible tube]," he said. "The treatment is not perfect. In some patient we do cause blocking of blood vessels by breaking off pieces of blood clots. If we could prevent that, mortality, which is now about 4 percent in one month after the procedure, can get even lower."
Angioplasty, how it is done and who should have it, is explained by the American Heart Association.