Angioplasty More Than 48 Hours after MI Without Benefit?

Summarized by Robert W. Griffith, MD
December 4, 2006

Summary

Angioplasty, with or without stent placement, provides no benefit in patients with 100% coronary artery blockage if it's done more than 48 hours after a heart attack.

Introduction

Angioplasty - the passage of a catheter from the groin (femoral) artery into a coronary artery to relieve obstruction - is a common procedure. However, there's a good time and a bad time to open a blocked coronary artery. It's accepted that opening an artery that's 100% blocked in the first 12 hours after a heart attack can restore the blood flow to the heart muscle, and is a potentially life-saving procedure. But angioplasty after the first 12 hours is more controversial.

NYU School of Medicine researchers have examined the benefits of opening coronary arteries 3 to 28 days after a heart attack, and published their findings in the New England Journal of Medicine. Here's a summary of their findings.

What was done

The study, called the Occluded Artery Trial or OAT, involved 2166 patients from 17 different cardiovascular centers around the world. The patients had to be stable, with a total occlusion of the affected artery, and defined as being at high risk (an ejection fraction¹ of less than 50%); their infarct had to have occurred between 3 and 28 days previously. They were excluded if they were in heart failure or shock, or they had severe coronary artery disease leading to angina or failed a stress test.

The patients were randomly assigned to one of two groups: balloon angioplasty (percutaneous coronary intervention, or PCI) with stent placement and optimal medical therapy, or optimal medical therapy alone. Optimal medical therapy included aspirin, anticoagulants, an ACE-inhibitor, a beta-blocker, and a lipid-lowering agent (e.g. Lipitor^®).

Their subsequent clinical course was followed for an average of 3 years. The end-points assessed were death, a new heart attack (reinfarction), or severe heart failure. The frequencies of such events were compared in the two groups of volunteers.

What was found

The average age of the patients was 59; 78% of them were men, and 81% were white. Of the 2166 patients enrolled, 1082 were randomly assigned to routine angioplasty plus optimal medical therapy, and1084 to optimal medical therapy alone. In those having angioplasty, 87% had stent placement, of which 8% were drug-eluting (drug-releasing) stents. Nine percent of the patients in the medication-only group crossed over - that is to say, they had angioplasty at some time after randomization, for medical resons.

After one year, the affected artery was considered 'open' on angiography in 83% of the angioplasty patients in whom this was assessed, and in 25% of the patients given medical therapy alone.

Comparison of the findings up to 4 years after infarction showed that angioplasty made no difference to the frequency of death, recurrent heart attack, or heart failure. These events were seen in 17.2% of the angioplasty group, and in 15.6% of the medical therapy group. There was a trend towards slightly more frequent recurrent heart attacks in the angioplasty patients: it occurred in 7.0% and 5.3% in the two groups, respectively.

These results were unaffected for possible differences related to age, gender, race, ejection fraction, diabetes, or the time from infarct to randomization.

What these findings mean

There are more than 100,000 heart attack survivors each year in the USA. As many as 30% of eligible patients may not receive angioplasty within the first 12 hours after their attack, because they get to hospital too late. Until now, this group had been considered candidates for late angioplasty, but this may change, in view of the results of this study. They showed that angioplasty provided no benefit in patients with 100% blockage, with no or only mild symptoms, when done more than 48 hours after their heart attack. Optimal medical therapy will do just as well, cost a lot less, and probably be less emotionally stressful.

Source

• Hochman JS, Lamas GA, Buller CE, et al. Coronary intervention for persistent occlusion after myocardial infarction. New Engl J Med 2006; http://content.nejm.org/cgi/content/short/NEJMoa066139

Footnotes
1. Ejection fraction: The ejection fraction is the amount of blood pumped divided by the amount of blood the ventricle contains. A normal ejection fraction is more than 55% of the blood volume. If the heart becomes enlarged, even if the amount of blood being pumped by the left ventricle remains the same, the relative fraction of blood being ejected decreases.

Related Links
Medline Plus: Angioplasty
Today, Women's Angioplasty Results Equal Men's
The Importance of Rehab after a Heart Attack

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