OAT study chair and Harold Snyder Family Professor of Cardiology， Clinical chief and director of the Cardiovascular Clinical Research Center at the New York University School of Medicine in New York City. The OAT trial sought to determine whether performing balloon angioplasty in a totally blocked coronary artery related to a heart attack three to 28 days after the heart attack would benefit stable patients and reduce the risk of future cardiovascular complications.
In angioplasty， a thin tube with a balloon or other device on the end is first 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. A total of 2，166 patients in 27 countries were randomly assigned to routine angioplasty with stenting combined with drug therapy or to drug therapy alone. Most patients had blockages in one coronary artery only.
Drug therapy for both groups included aspirin， blood-pressure lowering ACE inhibitors， beta blockers， cholesterol-lowering therapy， and clopidogrel， a drug given to patients with stents to prevent blood clots. Patients assigned to undergo angioplasty were given the procedure within 24 hours of treatment assignment. Stenting， placing a metal mesh tube in the artery to keep it open， was recommended for the patients given angioplasty. The primary endpoint or measured result of the 5-year study was a composite of death from any cause， another heart attack， or hospitalization for severe (Class IV) heart failure. The results 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 percent in the angioplasty group compared to 15.6 percent of the medical therapy group. The results were consistent across study sites located in the United States and in other countries. According to the results， stable patients who had angioplasty plus stenting three to 28 days after a heart attack did no better than patients on medical therapy (primarily drug treatment) alone. There is a trend of more heart attacks in the angioplasty group. Although the trend was not statistically significant， it needs to be studied and the patients followed for a longer time to determine if the trend continues or whether other trends emerge.
The explanation could be the following: when someone has a 100 percent blocked artery， the heart muscle may still be somewhat protected by small vessels that provide blood flow from the other coronary arteries. These vessels are so small that if an easier blood flow path is reestablished via angioplasty， they close down， either temporarily or permanently. If the artery that had the angioplasty re-closes， these small vessels would not be rapidly available to supply blood to your heart muscle at the time of your next heart attack. In addition， it is possible that some heart muscle damage due to dislodging of clots and plaque at the time of the angioplasty procedure counteracts other potential long-term benefits.