Angioplasty loses effect if not performed soon after heart attack

November 15, 2006

As the debate gathers steam about when, how, or if imaging techniques such as angiography with CT and MR should be used to follow heart patients after interventions, new research raises questions about whether the debate is relevant.

As the debate gathers steam about when, how, or if imaging techniques such as angiography with CT and MR should be used to follow heart patients after interventions, new research raises questions about whether the debate is relevant.

Patients who have no or only mild distress in the days following a heart attack do not reduce their risk of having another attack if they undergo angioplasty to mechanically open their totally blocked coronary arteries, according to researchers at New York University.

This contradicts a widespread medical belief that leads many physicians to perform the procedure when cardiac cath shows substantial blockage of one or more coronaries.

Opening completely blocked arteries with angioplasty in the first 12 hours after a heart attack can quickly restore vital blood flow to the heart and is still believed the optimal treatment for almost all patients. But U.S. physicians often open the blocked coronaries of stable patients who are beyond this treatment window.

"We had expected that angioplasty to open arteries would reduce the risk of subsequent clinical events, specifically heart failure and death, in this population that was stable after the initial heart attack but at increased risk of events in the future," said Dr. Judith S. Hochman, director of the Cardiovascular Clinical Research Center at the NYU School of Medicine and lead author of the study. "We thought it was possible that the risk of a recurrent heart attack would also be reduced. The results were surprising and do warrant a major change in practice."

The Occluded Artery Trial, presented Nov. 14 at the American Heart Association meeting in Chicago and due to be published Dec. 7 in the New England Journal of Medicine, evaluated whether opening arteries three to 28 days after a heart attack benefited patients over the long term. It was designed to provide definitive answers to questions about this practice, which could affect more than 100,000 heart attack survivors each year in the U.S., according to Hochman.

This block of patients represents the estimated one-third of heart attack survivors who do not undergo angioplasty within the treatment window. This usually happens because they arrive too late at the hospital.

Hochman noted that angioplasty has been proven to improve symptoms in patients with angina and to prolong life in patients if it's carried out shortly after a heart attack. In the study, investigators applied balloon angioplasty and inserted stents to open completely blocked coronary arteries in patients who were in stable condition, as is commonly done throughout the U.S.

More than 2000 patients at 217 sites on five continents were randomly assigned by computer to receive balloon angioplasty and stents plus medical therapy or medical therapy alone three to 28 days after their heart attack. Researchers tracked their health for an average of three years after the heart attack.

There was no statistically significant difference between the two groups in the occurrence of death, heart attacks, or heart failure through up to five years of follow-up, according to the study. In fact, the researchers observed a worrisome trend toward higher rates of repeat heart attack in the group receiving the angioplasty and stents. Hochman speculated that opening a totally blocked artery in a patient who has collateral blood flow may interfere with the ability of the collateral vessels to rapidly supply blood if the stented artery closes again.

"It seems that total occlusion is a stable situation and this may be converted to a potential risk for recurrent heart attack if the artery is opened and then reoccludes," she said.

Additionally, it is possible that some heart muscle may be damaged due to dislodging of clots and plaque at the time of the angioplasty procedure, counteracting other potential long-term benefits.

Further analysis and longer follow-up are necessary, however, as this observation did not reach the level of statistical significance, Hochman said. It could, therefore, have been due to chance alone.

The one certainty following the research is that heart attack patients must seek medical care immediately after the onset of symptoms of a heart attack to gain the most benefit from interventions. If they miss the reperfusion treatment window, they should be treated with medication, she said.

"Medical therapy has improved dramatically," Hochman said. "Those patients did quite well and better than projected."