American College of Cardiology

Metal-Strut Thickness Influences How Well Coronary Stents Keep Arteries Open

(ATLANTA)—Injury to the vessel wall is an unavoidable consequence of coronary stenting, in which a tiny metal scaffold is placed within a narrowed major heart vessel to keep blood flowing freely. The long-term healing response to this procedure largely determines how well the stent’s metal struts keep the vessel open. A new study has determined that narrower stent struts are associated with less vessel renarrowing than wider struts, regardless of the stent’s overall design.

A total of 611 patients with narrowed heart vessels were randomly allocated to stenting with either of two commercially available, differently designed stents in the ISAR-STEREO-2 trial. The two stents had different strut configurations, and the struts of one stent were nearly three times thicker than those of the other, said Dr. Helmut Schühlen, of the German Heart Center in Munich, Germany. The two stents were equally effective in the short term, said Dr. Schühlen; however, heart vessels treated with stents with thinner struts were significantly less likely to become renarrowed over the next six months.

Dr. Schühlen is slated to disclose the final results of ISAR-STEREO-2, the second Intracoronary Stenting and Angiographic results – Strut Thickness Effect on REstenosis Outcome trial, here on Sunday, March 17, at 8:45 a.m. at the American College of Cardiology 51st Annual Scientific Session.

Familiar Vasodilator, Added to Clot-Busters or Angioplasty, Further Limits Heart Attack Severity

(ATLANTA)—Physicians can choose from several “reperfusion therapies” to reestablish blood flow within obstructed heart vessels in patients experiencing an acute heart attack. Such treatments work partly by shrinking the ultimate extent of heart muscle damage, so researchers have been looking for add-on ways to enhance the effect. After lots of dead-ends in their search, investigators believe that an already familiar drug just might be what they are looking for.

In the second AMISTAD trial (Acute Myocardial Infarction Study of Adenosine II), more than 2,000 heart attack patients in 13 countries were randomly allocated to receive either a placebo or the intravenous vasodilator adenosine along with standard reperfusion therapy. The latter usually consists of either clot-busting medications or angioplasty, the catheter procedure that uses tiny balloons or metal scaffolds to widen heart vessels.

Patients who received adenosine at the higher of two dosages had 27 percent less heart muscle damage than did those who received the placebo, said Dr. Allan M. Ross, of George Washington University Medical Center, in Washington, D.C. That benefit was strongly associated with fewer deaths and later hospitalizations due to heart disease.

“Adenosine appears to be an effective supplemental treatment for victims of acute heart attack,” said Dr. Ross. He is slated to present the results of AMISTAD II here on Sunday, March 17, at 8:58 a.m. at the American College of Cardiology 51st Annual Scientific Session.

Study Tests Whether Standard Balloon Inflation Should Precede Stenting of Heart Arteries

(ATLANTA)—The traditional way to implant coronary stents, the metal scaffolds that can prop open narrowed heart vessels, requires that a tiny balloon first be inflated to widen the section of artery the stent will occupy. But in recent years, cardiologists have streamlined the procedure by inserting stents directly, that is, without such predilatation. There are important potential advantages of direct stenting, but whether it leaves the patient better off than the traditional approach has yet to be proved. An answer could come from a major randomized trial.

The Tetra Randomised European Direct Stenting Study (TRENDS), in which 1,000 patients were randomly assigned to stenting with or without predilatation, is expected to provide important insights about a procedure that is already common but for which little supporting evidence exists.

Dr. Keith D. Dawkins, of Wessex Cardiac Unit, Southampton in the United Kingdom, is slated to present the TRENDS primary 30-day results here on Sunday, March 17, at 9:10 a.m. at the American College of Cardiology 51st Annual Scientific Session.

(ATLANTA)—One of the most intensely watched areas of cardiology today is the use of coronary stents that elute, or slowly release, minute amounts of certain anti-inflammatory and immunity-suppressing medications. Now, a stent that elutes tacrolimus, a powerful immunosuppressant and anti-inflammatory agent, has been tested for safety and effectiveness in preventing tissue regrowth inside the stent. Such “in-stent restenosis” is a major limitation of conventional stents, the tiny metal scaffolds that can widen heart vessels.

If successful, the tacrolimus-eluting stent could potentially join the list of similar drug–stent combination devices that have been recently shown to prevent in-stent restenosis. Tacrolimus has been long available in larger doses as Prograf (Fujisawa, Japan), which is used for fighting organ transplant rejection.

The PRESENT (PREliminary Safety Evaluation of Nanoporous Tacrolimus eluting stents) trial tested a tacrolimus-eluting stent designed for coronary arteries, the major vessels that provide blood to heart tissue. The sister study EVIDENT (Endo-Vascular Investigation Determining the Safety of a New Tacrolimus Eluting Stent Graft) evaluated a tacrolimus-eluting “stent-graft” designed for diseased saphenous vein bypass grafts, the borrowed leg vein that is surgically attached to a coronary artery to reroute blood around severe narrowings.

Prof. Eberhard Grube, of the Heart Centre Siegburg in Germany, is scheduled to present results from the PRESENT and EVIDENT studies here on Sunday, March 17, at 9:22 a.m. at the American College of Cardiology 51st Annual Scientific Session.

(ATLANTA)—Coronary stents have dramatically improved cardiologists options for treating their patients, but these tiny scaffolds that widen diseased heart vessels have their limitations. In fact, techniques that may increase the effectiveness of stents remain an intense research area. Now a study has cast doubt on whether cutting away some of the vessel-blocking tissue from inside the artery, a procedure called directional atherectomy, can enhance the results of subsequent stenting. However, the study also hinted that the benefit of atherectomy may depend on how much tissue is removed.

In the “Atherectomy and Multilink stenting Improves Gain and Outcome” trial, or AMIGO, 755 patients with coronary disease were randomly assigned to undergo coronary stenting with or without prior lesion “debulking,” that is, partial blockage removal by directional atherectomy. The two groups showed no significant differences in outcome over eight months, said Dr. Antonio Colombo, who is scheduled to present the trial’s complete results here on Sunday, March 17, at 9:34 a.m. at the American College of Cardiology 51st Annual Scientific Session.

Data from some of the trial’s participating hospitals, observed Dr. Colombo, of Centro Cuore Columbus in Milan, Italy, suggested that the addition of atherectomy did improve the effectiveness of stenting when a large enough amount of blockage was removed.

(ATLANTA)—Researchers have hoped that coating stents with the blood-thinner heparin would improve these metal scaffolds as a treatment for some patients with narrowed heart vessels. But a multicenter trial has shown that such coated stents are no better than conventional ones at keeping open previously widened but renarrowed small heart vessels.

In the Heparin-Coated Stents in Small Coronary Arteries (COAST) trial, angioplasty balloons or stents with or without heparin coatings were used in 600 patients with recurrent small-vessel narrowings. Such patients are particularly challenging to treat. This is partly because small heart vessels may be more prone than larger ones to restenosis, a renarrowing process that is the major limitation of angioplasty—the widening of heart vessels using tiny balloons or scaffolding stents. Also, the risk of restenosis is especially high after second or third angioplasties.

After six months, none of the three treatment strategies proved better than another at keeping the small vessels open or preventing heart attacks or other cardiac problems, according to Dr. Michael Haude, of University Essen in Essen, Germany.

Dr. Haude is scheduled to present the COAST trial results here on Sunday, March 17, at 9:46 a.m. at the American College of Cardiology 51st Annual Scientific Session.

The American College of Cardiology, a 28,000-member nonprofit professional medical society and teaching institution, is dedicated to fostering optimal cardiovascular care and disease prevention through professional education, promotion of research, leadership in development of standards and guidelines, and the formulation of health care policy.

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