Using angioplasty to unclog arteries more than 24 hours after a patient's heart attack does no good and may increase the chances of another attack, researchers said today.
The findings contradict a long-held belief that opening vessels to restore blood flow is always beneficial and could spare thousands of patients from undergoing the costly and potentially risky procedure.
The report "is a sobering reminder that sometimes our preconceived notions turn out not to be accurate," said Dr. Prediman K. Shah, director of cardiology at Cedars-Sinai Medical Center, who was not involved in the research.
Dr. L. David Hillis of the University of Texas Southwestern said the study should bring an end to delayed angioplasties in stable heart attack patients. The surgery typically costs between $10,000 and $15,000, he said.
"There should be a substantial savings in patient discomfort and also monetarily," said Hillis, who coauthored an editorial on the study, both of which were posted on the website of the New England Journal of Medicine.
The study was presented today at the annual meeting of the American Heart Assn. in Chicago. The National Heart, Lung and Blood Institute paid for the study.
The study of more than 2,000 patients in 27 countries focused on the outcomes of angioplasties performed more than 24 hours and up to 28 days after the patients first developed symptoms of a heart attack.
Angioplasty involves threading a catheter through a blood vessel in the groin to the site of the blockage, which may be a blood clot or a buildup of plaque on artery walls. After a ballon is inflated to open the artery, a wire mesh tube, or stent, is typically positioned inside the vessel to keep it open.
If performed within 12 hours after a heart attack, the procedure can preserve heart muscle and reduce deaths, researchers said. That's why people who may be experiencing a heart attack are urged to get immediate help.
Previous research on angioplasties performed outside the crucial 12-hour window has produced conflicting results. Some studies found that the procedure offered little benefit. Others concluded that the restoration of blood flow improved patients' life expectancy even if the angioplasty came too late to salvage heart muscle.
About 100,000 people in the U.S. each year seek treatment for mild heart attacks caused by blockages after more than 12 hours have passed. Many of these patients delay getting help because they have vague symptoms and mistake their heart attacks for indigestion or muscle cramping. Roughly half of them undergo angioplasty.
The latest study divided 2,166 patients into two groups: One received standard medications to prevent blood clots and maintain heart rhythm; the second got the same drugs in addition to an angioplasty.
After four years, the groups had comparable incidences of death, serious heart failure or recurrent heart attacks.
"There was absolutely no benefit," said Dr. Judith Hochman, director of cardiovascular research at New York University and lead author of the report.
But there were worrisome indications that risks associated with angioplasty might increase over time.
At the end of five years, 21.2% of patients receiving angioplasty had another attack compared to 16.5% of group receiving only heart medications. Researchers said the difference was not statistically significant.
Hochman said researchers were very surprised to discover that angioplasty might leave patients worse off.
She said it was possible that the restoration of blood flow caused the shutdown of smaller vessels that had sprouted over time to handle some of the work of the clogged artery. In such a case, the smaller vessels would not be available to supply the heart if the angioplasty closed and caused a second heart attack.
Another possibility, she said, was that the benefits of restoring blood flow were offset by heart muscle damage caused by debris from blockages dislodged during the angioplasty procedure.