High dose Tirofiban Might be Beneficial among Poor Responders to Clopidogrel and Aspirin Following Elective PCI: Results of the 3T/2R study

September 2, 2008 by Leah H. Biller [mailto:lbiller@perfuse.org]

ESC Congress 2008- Munich, Germany: Investigators from Italy reported that for poor responders to standard oral antiplatelet agents, treatment with high-dose bolus (HDB) tirofiban after elective percutaneous coronary intervention (PCI) decreased the rate of periprocedural myocardial infarction compared to placebo.

The main results of the 3T/2R (Tailoring Treatment with Tirofiban in patients showing Resistance to aspirin or Resistance to clopidogrel) study were presented by Dr. Marco Valgimigli at the ESC 2008 Congress Hot Line Update III Session.

For patients undergoing PCI, the risk of plaque rupture has been combated with antiplatelet therapy as part of standard clinical practice. Studies have shown, however, that treatment with clopidogrel and aspirin (oral antiplatelet drugs) is not uniformly effective for all patients and in fact responsiveness to these drugs is markedly variable; moreover, poor responsiveness to clopidogrel has been linked to stent thrombosis, post-stent ischemic events and periprocedural myocardial infarction. The risk of thrombotic events after PCI has been shown to increase 1.8 to 10 fold for poor responders. While the individual patient’s response to cardiovascular drugs such as anti-hypertension and lipid lowering has been studied and is considered in planning treatment, individual responsiveness to oral antiplatelet agents has remained largely unaddressed.

The 3T/2R study aimed to investigate the potential role of HDB tirofiban to decrease thrombotic events for those patients with poor response to standard clopidogrel and aspirin therapy. Out of 1277 patients scheduled to undergo elective PCI for stable or low-risk coronary disease at ten European sites, 263 poor responders were selected based on point-of-care assays (VerifyNow™ Aspirin and P2Y12 assays (Accumetrics, USA)). Patients were randomized in a double blind manner to either HDB tirofiban (25µg/kg in 3 min followed by 14-24 hour infusion at 0.15µg/kg/min) or placebo with standard clopidogrel and aspirin. The primary endpoint was an increase in Troponin I or T elevation greater than 3 times the upper limit of normal (ULN) within 48 hours post-PCI, indicating a periprocedural myocardial infarction according to the universal definition.

Patients receiving HDB tirofiban had a decreased rate of periprocedural myocardial infarction compared to those receiving placebo plus standard therapy (20.4% versus 35.1% respectively; Relative Risk Reduction = 42%; 95% CI = 61-12; p = 0.009 for superiority). At 30-day follow-up, the HDB tirofiban group had a significant reduction in major adverse cardiovascular events (21.2% versus 36.6% for the placebo plus standard therapy group, p = 0.0065). Bleeding rates were low in both trial arms and not significantly different. The findings of the 3T/2R study suggest the importance of considering individual patients’ responsiveness to standard antiplatelet therapy (via point-of care assays); moreover, the results demonstrate proof of concept for the potential of HDB tirofiban treatment in poor responders. Further investigation should utilize additional methods of testing for clopidogrel and aspirin responsiveness.

It would have been nice to know what happens to patients who are aspirin and clopidogrel responders who recieved HDB (tirofiban). Why do we need to give aspirin and clopidogrel if HDB (tirofiban) is good enough?

The 3T/2R study was sponsored by the University of Ferrara, Italy. The study was supported in part by an unrestricted research grant from Merck, USA and Iroko, USA.