Drug-eluting and absorbable stents push interventional frontiers

Separate study fine-tunes timing of anti-clotting drugs

ATLANTA, GA (March 13, 2006) -- Medicated stents that prevent arterial renarrowing are offering hope to patients with certain types of cardiovascular disease, while a novel stent that slowly dissolves into the artery wall is proving to be a safe alternative to conventional devices, according to research presented today at the American College of Cardiology's inaugural Innovation in Intervention: i2 Summit 2006 in Atlanta, Ga. A separate study tests the best approach to prevent blood clots in patients with acute coronary syndromes. Innovation in Intervention: i2 Summit is an annual meeting for practicing cardiovascular interventionalists sponsored by the American College of Cardiology in partnership with the Society for Cardiovascular Angiography and Interventions.

Prospective, Randomized Comparison of Routine Upfront Initiation versus Selective Use of Glycoprotein IIb/IIIa Inhibitors in Patients with Acute Coronary Syndromes: The ACUITY Timing Trial

In patients with acute coronary syndromes, doctors are unclear about whether it is better to give glycoprotein IIb/IIIa inhibitors (GPI, which prevents platelets from clumping together to form a blood clot) to all patients in the emergency room, or wait for the results of angiography and give GPI only if angioplasty is needed to restore blood flow to the heart. The Acute Catheterization and Urgent Intervention Triage Strategy (ACUITY) Timing trial will answer that question.

Acute coronary syndrome (ACS) is an umbrella diagnosis that encompasses both unstable angina and a type of heart attack known as non-ST elevation myocardial infarction (NSTEMI). Today, drug therapy typically consists of aspirin, clopidogrel, heparin, and a glycoprotein IIb/IIIa inhibitor (GPI), each of which interferes with a specific step in blood clotting. Patients also typically have an angiography within a few days to determine whether further, invasive treatment with angioplasty or surgery is needed.

The main ACUITY trial was designed to compare heparin and the direct thrombin inhibitor bivalirudin in 13,820 patients with moderate-to-high-risk ACS. The results were reported on Sunday, March 12, at a Late Breaking Clinical Trial session.

The ACUITY Timing Trial was led by Dr. Gregg W. Stone, M.D., F.A.C.C., Columbia University Medical Center and the Cardiovascular Research Foundation, New York City. He and colleagues from 448 medical centers in 17 countries performed a second comparison, randomly assigning 9,200 patients to receive either upfront GPI (eptifibatide or tirofiban) in the emergency room, or delayed, selective GPI (eptifibatide or abciximab) in the cardiac catheterization laboratory, only if a coronary intervention were necessary. The study will evaluate the combined rates within 30 days of death, heart attack, or unplanned angioplasty or surgery to restore blood flow to the heart.

Dr. Stone will present the ACUITY Timing Trial at a Late Breaking Clinical Trials session on Monday, March 13, at 9:15 a.m.

A Prospective, Multicenter, Randomized Trial Evaluating the TAXUS Paclitaxel-Eluting Coronary Stent versus Vascular Brachytherapy for the Treatment of Bare Metal Stent In-Stent Restenosis: The TAXUS-V ISR Trial

When a plaque-filled coronary artery is opened and treated with a regular metal stent, it has a one-in-three chance of narrowing again due to scar tissue. Results of a multicenter, randomized trial will provide new insight into the comparative effectiveness of drug-eluting stents and radiation therapy for restoring blood flow through the blocked coronary stent.

Vascular brachytherapy (VBT)--or irradiation inside the narrowed artery--is the only therapy approved by the Food and Drug Administration for in-stent restenosis (ISR), as the renarrowing is called. However, brachytherapy is time-consuming, not widely available, and has been shadowed by complications. In the TAXUS-V ISR study, Gregg W. Stone, M.D., F.A.C.C., Columbia University Medical Center and the Cardiovascular Research Foundation, New York City, and fellow researchers from 37 North American medical centers set out to determine whether the TAXUS drug-eluting stent might offer a better alternative to VBT. Slow release of paclitaxel from the stent's surface has been shown to inhibit new growth of scar tissue in other types of patients, but its effectiveness against in-stent restenosis is unknown.

The study enrolled 421 patients with in-stent restenosis, randomly assigning them to VBT or repeat stenting with the TAXUS stent. After 30 days, the two approaches appeared to be equally safe, with similar rates of cardiac death, heart attack, coronary procedures, and blood clotting in the stent. Investigators also evaluated clinical outcomes after nine months of follow-up, as well as the results of angiography and intravascular ultrasound, two imaging studies that can detect changes in the artery over time.

Dr. Stone will present the TAXUS-V ISR study at a Late Breaking Clinical Trials session on Sunday, March 12, at 9:45 a.m.

Final Results of the TYPHOON Study, a Multicenter Randomized Trial Comparing the Use of Sirolimus-Eluting Stents to Bare Metal Stents in Primary Angioplasty for Acute Myocardial Infarction

Angioplasty and stenting are the most effective ways to open a coronary artery and restore blood flow to the heart after a heart attack, or acute myocardial infarction (MI). However, it is uncertain whether drug-eluting stents--which have been shown to prevent late arterial renarrowing, or restenosis, in patients with stable coronary artery disease--are suitable for treatment of acute MI.

To address that question, investigators from the Trial to Assess the Use of the Cypher Stent in Acute Myocardial Infarction Treated with Angioplasty (TYPHOON) randomly assigned 712 patients who experienced an acute MI to artery-opening treatment with either a bare-metal stent or a Cypher stent. The Cypher stent slowly releases sirolimus, a medication that prevents the overgrowth of scar tissue that can cause restenosis in the months after stenting. Investigators from 48 medical centers participated in the study.

To assess the effectiveness and safety of the Cypher stent, investigators have analyzed target vessel failure at one year, as gauged by the need for a procedure to re-open the heart-attack-related artery, repeat MI, or cardiac death. They also performed a substudy that uses angiography to evaluate changes in arterial diameter, and documented stent-related complications.

"Our findings could have important clinical implications," said Christian Spaulding, M.D., a professor of cardiology at Assistance Publique-Paris University Hospitals, Paris, France. "Sirolimus-eluting stents are not currently recommended in the acute phase of myocardial infarction, since no clear data from a randomized trial are available. The use of sirolimus-eluting stents in acute MI could, therefore, reduce the rate of clinical events and repeat procedures."

Dr. Spaulding will present the TYPHOON study results in a Late Breaking Clinical Trial session on Sunday, March 12, at 9 a.m.

The Coronary Results of the First Absorbable Metal Stent: The PROGRESS-I Trial

A new type of stent that props open the artery during healing, but is then absorbed into the artery wall is proving to be a safe alternative to conventional, permanent stents, in the first study in humans with coronary artery disease.

"The absorbable metal stent is not just another stent," said Raimund Erbel, M.D., F.A.C.C., University Essen, Germany. "It represents a revolutionary leap forward in vascular interventional treatment."

The new stent is made of a proprietary magnesium alloy that allows it to provide scaffolding to the vessel wall for approximately two months before being absorbed. It has intriguing potential advantages over a permanent stent because it would not be subjected to long-term mechanical stress, for example, or stimulate a biological interaction with the artery wall. Future catheter procedures would be simplified. Equally as important, noninvasive imaging of the treated artery would also be possible with these stents. Currently, patients with permanent metal stents cannot safely undergo a magnetic resonance imaging scan, and images taken through a stent are often unclear with computed tomography.

To determine whether absorbable metal stents are safe and effective, Dr. Erbel and his colleagues at nine medical centers used the new device to treat 63 patients with plaque build-up in a single coronary artery. During the first four months of follow-up, they observed no alarming complications, including blockage of the stent with a blood clot, heart attack, or death. Using angiography and intravascular ultrasound, they also evaluated whether the artery became narrowed over time.

Dr. Erbel will present the PROGRESS-I study at a Late Breaking Clinical Trials session on Monday, March 13, at 9:45 a.m.

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The American College of Cardiology (www.acc.org) represents the majority of board certified cardiovascular physicians in the United States. Its mission is to advocate for quality cardiovascular care through education, research, promotion, development and application of standards and guidelines- and to influence health care policy. ACC.06 and the ACC inaugural i2 Summit, the first-ever meeting for interventional cardiologists, will bring together more than 30,000 cardiologists and cardiovascular specialists to share the newest discoveries in treatment and prevention, while helping the ACC achieve its mission to address and improve issues in cardiovascular medicine.

Innovation in Intervention: i2 Summit is an annual meeting for those practicing coronary and non-coronary interventions. Sponsored by the American College of Cardiology, in partnership with the Society for Cardiovascular Angiography and Interventions and other professional associations, i2 Summit 2006 offers late-breaking interventional clinical trials, peripheral, vascular, coronary and valvular education, live cases from Europe, Asia and the United States, emerging technology / state-of-the-art lectures, expert simulation demonstrations, interactive Laptop Learning and general cardiovascular education at ACC.06, held concurrently with i2 Summit, for a dynamic, complete cardiovascular educational experience. i2 Summit consolidates all clinical, educational, practical and community needs into one event and delivers unsurpassed needs-based learning with true objectivity.


Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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