New Tack on Heart Attacks Could Save Lives

April 4, 2002 -- The method used for treating heart attacks in this country for more than 15 years has been called into question by a landmark study, which suggests that thousands of lives could be saved by a new approach.

The momentum for a change is so strong that one major U.S. city has already taken steps to implement it, and there are signs that heart specialists overseas are rethinking their strategy as well.

Since 1986, heart attacks have been treated by giving patients drugs called clot-busters, which break up the clots in the artery that cause heart attacks. But in recent years, hospitals with special cardiac catheterization laboratories have been bringing heart attack patients into these labs, inserting a catheter, and opening up the artery with a tiny balloon.

This approach was considered too costly and too slow to be effective, since it required bringing the patient into a laboratory and doing a procedure.

But a study from Denmark suggests that the "cath lab" treatment for heart attacks when compared to clot-busters actually saved lives, even if patients had to travel to other hospitals to receive it.

"This could result in the saving of more than 10,000 lives per year in the U.S. alone, and the prevention of countless heart attacks and needless strokes," said Dr. Gregg Stone, director of cardiovascular research and education at the Lenox Hill Heart and Vascular Institute in New York.

"I think that it will [change current practice]," added Dr. David Faxon, president of the American Heart Association. "How much, I don't know."

Study Looked at Patients Transferred to Cath Labs

The Danish Myocardial Infarction Study II, or DANAMI II, explored the possibility of transferring patients suffering from certain heart attacks from community facilities that could not perform angioplasty to hospitals with invasive cath labs. The patients were experiencing a sub-type of heart attack known as ST elevation that accounts for roughly 40 percent of heart attacks in the United States.

The study was designed to enroll 1,900 patients, but was stopped after only 1,572 were enrolled, because one strategy was significantly more effective than the other.

Transferred patients had a 40 percent reduction in risk of death, reblockage of the artery or stroke after 30 days compared to the clot-buster group — even though making a transfer took longer.

The study's results were presented last month at the annual meeting of the American College of Cardiology in Atlanta.

"An initial strategy of [angioplasty] is superior to [clot-busters] for patients with [certain] heart attacks if the patients can be transferred to an invasive cath lab within three hours after diagnosis," said Dr. Henning Rud Andersen, an investigator on the trial who says these results will soon change the way that heart attacks are treated in Denmark.

Speed vs. Efficacy

"What is so fascinating about DANAMI is that it is suggesting that time may not be quite as critical as we may have thought," said Dr. Joe Ornato, chairman of the department of emergency medicine at Virginia Commonwealth University in Richmond, Va.

As one medical saying goes, "time is myocardium," or heart muscle — the longer you wait to treat a heart attack, the more damage is done by the lack of blood flow to heart muscle. That's why there is currently a two-hour "door to balloon" guideline on performing angioplasty, and why clot-busters — which can be administered in as little as 30 minutes in some cases — are the alternative.

But time isn't the only factor — success also depends on how well a given treatment is able to restore blood flow to heart muscle. And several studies have shown that angioplasty is superior in that regard. It restores good flow about 90 percent of the time compared to roughly half of the time for clot-busters.

"I think that's the explanation for why you can wait a little while with angioplasty and still get very good results," said Faxon. "Because it must be that better blood flow is more important than time."

In fact, according to Dr. Christopher Cannon, a cardiologist at Brigham and Women's Hospital in Boston, this is the 21st consecutive randomized trial to demonstrate the superiority of angioplasty. This large body of evidence is the reason why Boston-area hospitals and Boston Emergency Medical Services are taking steps to transfer all heart attack patients to hospitals that perform angioplasty.

"We're doing this in the setting of monitoring how quickly we do things and making sure that if we're going to do it — we're going to do it well," said Cannon. "We're gearing up that monitoring right now and in about six months we'll implement the bypassing of the non-angioplasty hospitals."

Ideal vs. Real Treatment Options

The results of the DANAMI trial are exciting to many heart experts — but changing heart attack treatment strategy on a national level is far easier said than done. Only 10 percent to 20 percent of hospitals in the United States have cath labs — leaving the overwhelming majority unable to provide the procedure.

And while the trial opens the window a little more, time is still a critical feature.

"The difference [between the two DANAMI II trial] groups seems only statistically significant if cath can be accomplished within three hours," said Dr. Richard O'Brien, a spokesman for the American College of Emergency Physicians who practices at a community hospital in Philadelphia. "That's a tough time limit in a lot of real world cath labs."

Many emergency departments are overworked and overcrowded — making it difficult to treat heart attack patients within the current two-hour time limit even within hospitals already equipped to perform angioplasty. Adding the time it takes to transfer a patient to another hospital can easily stretch the "door to balloon" time beyond acceptable limits — making treatment with a clot-buster much more attractive.

The results of this trial will likely be the subject of considerable debate among cardiologists on all sides of the issue, as it has the potential to add to the burden of already strapped cath labs and take heart attack patients away from smaller hospitals. Additionally, more hospitals may need to consider taking on the expense of putting in invasive cath labs of their own.

Yet regardless of these debates, many are convinced that the winds of change are blowing strongly in favor initial treatment with angioplasty.

"I think [this study] adds a lot of weight to say that [angioplasty] is better," said Cannon. "Why would we want to offer two standards of care depending on what hospital a patient happens to land in? This will be the beginning of a major change that may take five or six years to accomplish, but the process of developing a national approach is beginning."