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Angioplasty Timing Critical to Outcome
< Nov. 15, 2006 > -- Having an angioplasty within twelve hours of a heart attack improves long term survival and reduces the risk of a second heart attack.
Using the procedure more than three days after an attack does no good, a new study finds.
Angioplasty, also called percutaneous transluminal coronary angioplasty (PTCA) or percutaneous coronary intervention (PCI) uses a small balloon at the tip of a long catheter (thin hollow tube) to open an artery.
"These particular patients [who do not get the procedure close to the time of the heart attack] do not benefit from angioplasty," says Dr. Judith Hochman, lead author of the study and clinical chief of cardiology at New York University School of Medicine in New York City.
The bottom line, according to Dr. Hochman: "If you don't need an intervention, it's better not to have one."
The findings are published in the New England Journal of Medicine to coincide with a presentation this week at the annual meeting of the American Heart Association in Chicago.
The trial is considered a "negative" study because it failed to show a benefit.
"Negative studies contribute to our understanding of what is really important," says Dr. Ray Gibbons, president of the American Heart Association. "This is a good example of a negative study that will improve the efficiency of health care in this country. The US health care system is remarkably inefficient."
Right now, standard practice is to open arteries that are 100 percent blocked in the first 12 hours after a heart attack. But according to an accompanying editorial in the journal, the practice has been widely adopted even after that time window closes, despite the absence of good evidence to support it.
The newly released study sought to define the window of opportunity more specifically.
"We hypothesized that patients with a totally blocked artery would benefit from opening it in addition to using proven medications [after the initial 12 hours]," Dr. Hochman states.
The 2,166 stable patients in this study had 100 percent blockage of the heart attack-related artery three to 28 days after the initial heart attack. Because of this, they were considered at high risk for further cardiovascular events.
Participants were randomized to receive either angioplasty and stenting with drug therapy or drug therapy alone.
The results turned out to be the opposite of what the researchers expected.
During an average three years follow-up, they found no statistically significant difference between the two groups in rates of repeat heart attacks, heart failure, or death. In fact, the group that received angioplasty showed a troubling trend toward repeat heart attacks, although it was not clear if this was due to chance.
"We expected that the chance of death, development of severe heart failure, or another heart attack would be reduced 25 percent by adding angioplasty to optimal medical therapy. We didn't find that," Dr. Hochman says.
"It turns out that both groups were on excellent medical therapy, so we now emphasize secondary prevention such as stopping smoking, losing weight and controlling diabetes and high blood pressure," she adds.
It is not clear why the findings turned out the way they did, although it is possible that opening a blocked artery may interfere with the ability of smaller vessels to provide additional blood flow.
Always consult your physician for more information.
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Percutaneous transluminal coronary angioplasty (PTCA) is performed to open blocked coronary arteries caused by coronary artery disease (CAD) and to restore arterial blood flow to the heart tissue without open-heart surgery.
A special catheter (long hollow tube) is inserted into the coronary artery to be treated. This catheter has a tiny balloon at its tip. The balloon is inflated once the catheter has been placed into the narrowed area of the coronary artery. The inflation of the balloon compresses the fatty tissue in the artery and makes a larger opening inside the artery for improved blood flow.
In the past few years, many refinements have been developed in the PTCA procedure. One common procedure used in PTCA is stent placement.
A stent is a tiny, expandable metal coil that is inserted into the newly-opened area of the artery to help keep the artery from narrowing or closing again.
Once the stent has been placed, tissue will begin to form over it within a few days after the procedure. The stent will be completely covered by tissue within a month or so.
Newer stents (drug-eluting stents, or DES) are coated with medication to prevent the formation of scar tissue inside the stent.
These drug-eluting stents release medication within the blood vessel itself. This medication inhibits the overgrowth of tissue that can occur within the stent. The effect of this medication is to deter the narrowing of the newly stented blood vessel.
It is often necessary to take a medication, such as aspirin or clopidogrel (Plavix™), which decreases the “stickiness” of platelets (a type of blood cells that clump together to form clots to stop bleeding), in order to prevent blood clots from forming inside the stent.
Always consult your physician for more information.
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