New research has overturned one of the most fundamental beliefs among doctors treating heart attacks: that opening a blocked artery is always a good idea, even days or weeks later.

Instead, the study revealed that doing this too late may not help, and there were disturbing hints that it might even be harmful. People who had balloon angioplasty to open an artery three to 28 days after their heart attacks fared no better than those given standard medicines to prevent a second attack.

The latest figures from the Canadian Institute of Health Information suggest up to half of Canadians have not been getting their angioplasties within the study's acceptable wait time.

"These findings were really a surprise," said Dr. Elizabeth Nabel, director of the National Heart, Lung and Blood Institute, which funded the large international study. "For a long time we thought that opening up the artery any time after a heart attack was better than leaving it closed. My guess is you may see some guideline recommendations" on what to do in such situations, she said.

Urgent action

Opening arteries quickly is crucial to surviving heart attacks, and the study's findings do not change the need for urgent action or the evidence that angioplasty saves lives when done soon after an attack.

Nearly one million heart attacks occur in the United States each year, typically when a vessel squeezes shut, preventing enough blood and oxygen from reaching the heart.

The usual treatment is angioplasty, in which doctors snake a tube through a blood vessel in the groin to the blockage. A tiny balloon is inflated and a mesh stent is put in place to prop the artery open.

But one-third of heart attack victims do not seek care within 12 hours, when angioplasty has the best chance of helping. And sometimes, clot-dissolving drugs don't work to clear a blockage. No guidelines say what to do in such situations, but most doctors assumed that an angioplasty, even if done late, still would help prevent further damage to the heart muscle and future heart attacks.

This bias was so strong that the study took more than five years to recruit enough patients because doctors were unwilling to risk randomly assigning some of them to drug treatment alone, said Dr. Judith Hochman, cardiovascular research chief at New York University School of Medicine.

Some studies suggested "that if you left the hospital with an open artery, you did better over the long term," but this had never been firmly tested, said Hochman, who led the new study and gave results Tuesday at an American Heart Association conference.

They also were published online by the New England Journal of Medicine and will appear in its Dec. 7 issue.

Worrisome trend

Researchers enrolled 2,166 people in 27 countries to receive one of the following:

• Medicines alone.
• Angioplasty three to 28 days after a heart attack along with standard drug treatment (which included medicines to lower blood pressure and cholesterol, as well as Aspirin and other anti-clotting drugs).

These were patients who had survived their original heart attack but had a single vessel completely blocked, yet were stable because the heart was still receiving sufficient blood and oxygen from other vessels.

Four years later, 17 per cent of those given angioplasty and drugs and nearly 16 per cent of those given drugs alone had either died, suffered another heart attack or developed heart failure — results considered to be statistically the same.

There was a worrisome trend toward more heart attacks in the angioplasty group — seven per cent versus five per cent of the others — as time went on, though this could have been a statistical fluke, Hochman said.

The lack of benefit from angioplasty was not because the procedure didn't work — it successfully reopened arteries more than 90 per cent of the time, Hochman said.

Seek medical care quickly for heart attacks

Instead, the findings suggest that once a blocked vessel had caused a heart attack, opening it was no better than taking standard medications for preventing future problems.

"There is a reason to rethink angioplasty" in such situations, said Dr. Timothy Gardner, a cardiologist at Christiana Care Health Services in Wilmington, Del., and chairman of the Heart Association program committee that reviewed the research.

Angioplasty did seem to help prevent chest pain years after the procedure, Hochman said.

Most people have angioplasties in non-emergency situations to relieve chest pain and this research does not apply to them.

The new study underscores the importance of fast medical help for heart attacks.

"If you have symptoms of a heart attack, consult your doctor as soon as possible, and that includes calling 911 to get an ambulance … instead of driving yourself to the hospital, and get the proper medical advice," said cardiologist Dr. Luc Bilodeau of the Montreal Heart Institute, one of the doctors who took part in the study.

A dozen or so companies donated drugs and devices for the study and many of the researchers have consulted for them. The federal government paid 94 per cent of the study's cost.