Adding the glycoprotein IIb/IIIa inhibitor tirofiban to conventional aspirin and clopidogrel treatment in patients undergoing PCI improved outcomes even in the long-term, emphasizing the importance of platelet inhibitation even in elective PCI procedures, according to the results of an analysis of the TOPSTAR trial published in the April issue of the Journal of Invasive Cardiology.
Bjoern Lengenfelder, MD, of the Center for Cardiology in Lüneburg, Germany, and colleagues conducted a substudy of the TOPSTAR trial, a randomized, placebo-controlled trial to study the effects of the addition of a glycoprotein IIb/IIIa inhibitor tirofiban (Aggrastat, Medicure) to conventional aspirin and clopidogrel (Plavix, Bristol-Myers Squibb/Sanofi-Aventis) treatment in patients undergoing PCI.
“Platelet glycoprotein (GP) IIb/IIIa inhibitors are widely used in the treatment of acute coronary syndromes and as an adjunctive therapeutic option in percutaneous coronary interventions (PCI),” the authors wrote. However, data evaluating the long-term benefit of GP IIb/IIIa inhibitors remain sparse.
While the TOPSTAR trial in 2002 showed a lower periprocedural troponin release and lower six-month mortality risk following PCI, the current analysis sought to evaluate the long-term effects of this treatment in the 96 enrolled patients who were followed for four years.
The study used all-cause mortality and composite endpoints of all-cause death, MI and target vessel revascularization as the study’s main endpoints.
Lengenfelder et al reported that rates of all-cause mortality were higher in the placebo arm compared to the tirofiban arm, 10.9 percent vs. 0 percent. The composite endpoint occurred in 21.7 percent of patients in the placebo arm compared to 8 percent of patients in the tirofiban arm.
In addition, the researchers reported that 34.7 percent of the tirofiban patients were rehospitalized during follow-up for cardiac reasons compared with 31 percent of patients in the placebo arm. Recurrent angina and re-angiography was the frequent cause of rehospitalization, 58.8 percent in the tirofiban group vs. 61.5 percent in the placebo group. Angina without re-angiography occurred at rates of 11.8 percent and 15.4 percent, respectively.
A hospital readmission due to pacemaker implants occurred in 23.5 percent of patients in the tirofiban arm and 15.4 percent in the placebo arm.
“The success of platelet GP IIb/IIIa inhibitors in the treatment of acute MI and as an adjunct therapy in PCI and intracoronary stenting has led to their consideration as potential agents to enhance the efficiency of antithrombotic therapy,” the authors noted. “The current results provide new insights into the long-term effects of tirofiban therapy in patients undergoing PCI.”
The current results showed that in the long-term, inhibition of platelet aggregation with tirofiban in elective PCI procedures is beneficial in terms of survival as well as other composite endpoints. However, the authors said that larger studies will be necessary to evaluate the benefits of oral or intravenous platelet inhibition in terms of mortality MI or hospital readmissions in low-risk patient populations.
“The TOPSTAR trial could demonstrate for the first time a short- and long-term improvement in patient outcomes with planned elective PCI using the reversible GP IIb/IIIa inhibitor tirofiban in addition to aspirin and clopidogrel,” the authors concluded. “The results underline the importance and benefits of effective peri- and post-interventional platelet inhibition on post-interventional outcomes, even in elective planned coronary interventions.”