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November 20, 2006
Study of Late Angioplasty after Heart Attack
About a third of heart attack patients don’t receive treatment to open blocked arteries within the recommended 12-hour timeframe after a heart attack. For years, people thought that late balloon angioplasty of totally blocked arteries could still prevent future heart problems. According to the results of a large clinical trial, however, stable patients undergoing angioplasty plus stenting three to 28 days after a heart attack did no better than patients on drug therapy alone.
Each year, about one million people in the U.S. have a heart attack, and half of them die. About half of those who die do so within an hour of the start of symptoms and before reaching the hospital. In angioplasty, a thin tube with a balloon or other device on the end is threaded through a blood vessel in the arm or groin (upper thigh) up to the site of a narrowing or blockage in a coronary artery. Once in place, the balloon is then inflated to push the plaque outward against the wall of the artery, widening the artery and restoring the flow of blood through it.
The Occluded Artery Trial (OAT), which was funded by NIH’s National Heart, Lung, and Blood Institute (NHLBI), sought to determine whether it really benefited stable patients to perform balloon angioplasty three to 28 days after a heart attack in a totally blocked coronary artery related to the heart attack. A total of 2,166 patients in 27 countries were randomly assigned to receive routine angioplasty with stenting (placing a metal mesh tube in the artery to keep it open) combined with drug therapy, or drug therapy alone. The results were published online on November 14 in the New England Journal of Medicine.
The OAT trial found no statistically significant difference in major cardiovascular events between the two groups over an average of three years and up to five years. At four years, the rate of death, heart attack or serious heart failure was 17.2% in the angioplasty group compared to 15.6% of the medical therapy group. The trend toward more heart attacks in the angioplasty group was not statistically significant, but the patients will need to be followed for a longer time to see if any significant trends do emerge.
"These results challenge the long-standing belief that opening a blocked artery is always good," said NHLBI Director Dr. Elizabeth G. Nabel. The late opening of a coronary artery involved in a heart attack, the investigators concluded, should be reserved only for certain patients, such as those who are unstable or continue to have chest pain after a heart attack.
"There's an important public health lesson to be learned from the OAT trial results: seek care very early after heart attack symptoms begin, because that's when there is a great deal of benefit from angioplasty," said Dr. Alice Mascette, chief of NHLBI's Heart Failure and Arrhythmias Branch. "And we should not forget that controlling the risk factors for heart disease — such as high cholesterol and high blood pressure — can go a long way toward preventing heart attack in the first place."