New Type of Artery Stent Shows Promise
A new generation of stents shows promise in avoiding the late-onset problems that have plagued drug-eluting stents in patients with heart disease, researchers say.
The findings come from two European studies presented at the annual scientific meeting of the American Heart Association.
The tiny mesh tubes called stents are intended to prop open narrowed arteries, but this new stent works in a novel way.
It is coated with an antibody that provokes cells lining artery walls to migrate to and cover the stent, thus speeding the healing process and keeping arteries open longer.
"This is kind of the third-generation stent,” says Dr. Gregory Dehmer, at Texas A&M Health Science Center College of Medicine.
“One could even call these 'smart' or 'smarter' stents, because they are designed to deal with some of the problems that have existed in the earlier versions," he notes. "It's an exciting development, but . . . we have to temper our enthusiasm with the growing knowledge that some of the problems with drug-eluting [emitting] stents didn't show up for two to three years."
Even with continued promising results, the new device is likely years away from the US market.
"The [US Food and Drug Administration] FDA has largely taken a position of making companies repeat their studies here in the US," says Dr. John P. Reilly, at Ochsner Health System in New Orleans. "It will probably be three years before the technology comes to the US."
Stents are used in patients undergoing angioplasty procedures that reopen narrowed arteries. Bare metal stents were used first, but patients often had to undergo repeat procedures.
Drug-eluting stents, coated with slow-release drugs to prevent the vessel from closing up again, came next. But these also had limitations, namely late-stent thrombosis, or stent-related blood clots.
"The drug-eluting stents are doing exactly what they were designed to do, which is inhibit the excessive tissue growth after the injury from the balloon angioplasty or bare metal stent platelet, and they are doing it well," Dr. Dehmer says.
"The problem is that, at the same time, they are also inhibiting the normal healing response, or the cell growth that covers up the metal stent drugs and incorporates it into the vessel wall," he says.
The new stent is known as an "endothelial progenitor cell-capturing" (EPC) stent. As their name implies, endothelial progenitor cells are those that have the ability to differentiate into endothelial cells, or those cells that line the walls of the arteries.
The first study, by German researchers at Muller Hospital Munich, presented data on 1,640 "real world" patients, mean age almost 63 years old. One-quarter of the patients had diabetes, two-thirds had high blood pressure, one-quarter were current smokers, and more than one-third had had a prior heart attack.
Almost 74 percent of the participants received statin medications (which include Crestor®, Lipitor®, or Zocor®) prior to stenting. This family of cholesterol-lowering drugs also stimulates the number of endothelial progenitor cells in the blood.
At one year, only 1 percent of participants receiving the new stent had experienced a stent-related blood clot, 5.4 percent needed a revascularization on the same artery, and 5.1 percent underwent a catheter-based procedure to restore blood flow.
Just over 9 percent had a major adverse cardiac event such as a heart attack, unanticipated bypass surgery, or death. Just over 2 percent of patients died of cardiac causes, 1.8 percent of which were heart attacks.
The second study involved 236 patients at the Academic Medical Center of the University of Amsterdam in the Netherlands. All were treated with the EPC stent. The average age here was 65.
Three patients (1.2 percent) suffered stent thrombosis, and 10.2 percent required a repeat revascularization procedure of the same vessel.
Almost 14 percent suffered a major adverse cardiac event (2.5 percent of all patients had a heart attack), and 3 percent died, 0.8 percent of cardiac causes.
According to the study authors, these numbers were as good or better than those for drug-eluting stents.
One expert was encouraged by the findings.
"Earlier work indicated this line of investigation might be fruitful, but the magnitude of benefit with EPC-capturing stents in this study is a little surprising," said Dr. Kirk Garratt, at Lenox Hill Hospital in New York City.
"The target lesion revascularization (TLR) rates ran about 5 percent, even for diabetics, which is at least as low as we've seen with drug-eluting stents,” says Dr. Garratt.
“The ongoing work with higher-risk patient groups is also very encouraging. It's looking like EPC-capturing stents might be an excellent alternative to drug-eluting stents, and will only require a short course of dual antiplatelet drugs," he says.
And Dr. Garratt was impressed by the device's safety profile, as well.
"Of the several biological approaches under study to improve coronary stent results, this approach is among the most benign," he says. "It doesn't involve potent cellular or genetic manipulations that could have unexpected consequences. In that regard, this should be a safer approach."
Always consult your physician for more information.
Treatment for coronary artery disease may include:
modification of risk factors - risk factors that may be modified include smoking, elevated cholesterol levels, elevated blood glucose levels, lack of exercise, poor dietary habits, being overweight/obese, and elevated blood pressure.
medications - medications that may be used to treat coronary artery disease include:
- antiplatelet medications - medications used to decrease the ability of platelets in the blood to stick together and cause clots. Aspirin, clopidogrel (Plavix®), ticlopidine (Ticlid®), and dipyridamole (Persantine®) are examples of antiplatelet medications.
- anticoagulants - also described as "blood thinners," these medications work differently than antiplatelet medications to decrease the ability of the blood to clot. An example of an anticoagulant is warfarin (Coumadin®).
- antihyperlipidemics - medications used to lower lipids (fats) in the blood, particularly low density lipid (LDL) cholesterol. Statins are a group of antihyperlipidemic medications, and include simvastatin (Zocor®), atorvastatin (Lipitor®), and pravastatin (Pravachol®), among others. Bile acid sequestrants - colesevelam, cholestyramine and colestipol - and nicotinic acid (niacin) are two other types of medications that may be used to reduce cholesterol levels.
- antihypertensives - medications used to lower blood pressure. There are several different groups of medications which act in different ways to lower blood pressure
coronary angioplasty - a balloon is used to create a bigger opening in the vessel to increase blood flow. Although angioplasty is performed in other blood vessels, percutaneous coronary intervention (PCI) refers to angioplasty in the coronary arteries to permit more blood flow into the heart.
There are several types of PCI procedures, including:
- balloon angioplasty - a small balloon is inflated inside the blocked artery to open the blocked area.
- coronary artery stent - a tiny coil is expanded inside the blocked artery to open the blocked area and is left in place to keep the artery open.
- atherectomy - the blocked area inside the artery is cut away by a tiny device on the end of a catheter.
- laser angioplasty - a laser used to "vaporize" the blockage in the artery.
coronary artery bypass - most commonly referred to as simply "bypass surgery," this surgery is often performed in people who have angina (chest pain) and coronary artery disease (where plaque has built up in the arteries). During the surgery, a bypass is created by grafting a piece of a vein above and below the blocked area of a coronary artery, enabling blood to flow around the obstruction. Veins are usually taken from the leg, but arteries from the chest or arm may also be used to create a bypass graft.
Always consult your physician for more information.