Researchers evaluate efficacy, safety of anti-clotting drugs

Patients admitted to the hospital with an acute coronary syndrome (ACS) are often treated with a catheter-based procedure known as percutaneous coronary intervention, or PCI.

But doctors are unclear about the optimal antithrombotic therapy to prescribe after procedure to prevent clotting, and new research suggests a possible alternative, according to a study presented today at the American College of Cardiology's 55th Annual Scientific Session.

Previous research has shown that adding the antithrombotic drug abciximab, (a glycoprotein IIb/IIIa receptor inhibitor) to therapy with ticlopidine plus aspirin significantly reduces post-stent implantation complications, including death, repeat heart attack or reintervention. The drug ticlopidine has been replaced by clopidogrel in recent research, which is safe and acts more rapidly in a 600 mg dosage level, offering better platelet inhibition within two hours of administration.

In a previous trial of low-to-moderate risk patients, the use of clopidogrel was associated with such a low frequency of early complications that the use of abciximab offered no clinical benefit. However, higher risk patients with ACS may benefit from a more potent antithrombotic regimen. The ISAR-REACT 2 trial evaluated for the first time the value of abciximab in patients with ACS undergoing PCI after pretreatment with 600 mg of clopidogrel.

"No specifically designed randomized studies have previously been conducted on the value of abciximab plus a high-dose of clopidogrel during PCI in ACS patients," said Adnan Kastrati, M.D., of the Deutscshes Herzzentrum Munich, Germany and lead author of the study. "Together with other current trials, this will help to define the current optimal adjunct antithrombotic therapy in patients with ACS managed with PCI."

The randomized, multi-center, double-blind, placebo controlled study of 2,022 patients undergoing PCI after pretreatment with clopidogrel were randomized to receive abciximab or placebo. The researchers measured for 30-day combined incidence of death, heart attack or urgent revascularization, as well as bleeding complications. The trial results show the role of the combination - intensive clopidogrel pretreatment plus abciximab - during PCI for ACS. They will enable us to know whether patients with ACS or any subset of them can benefit from this combination.

Dr. Kastrati will present the results of the "Prospective, Double Blind, Placebo-Controlled Trial of Glycoprotein IIb/IIIa Inhibition with Abciximab in Patients with Acute Coronary Syndromes Undergoing Stenting After Pretreatment with a High Loading Dose of Clopidogrel"