TRIGGER-PCI Trial Results Published

April 24, 2012—Results of the TRIGGER-PCI (Testing Platelet Reactivity in Patients Undergoing Elective Stent Placement on Clopidogrel to Guide Alternative Therapy With Prasugrel) study by Dietmar Trenk, PhD, et al were made available on April 18 via expedited publication online on ahead of print in the Journal of the American College of Cardiology.

TRIGGER-PCI sought to investigate the efficacy, safety, and antiplatelet effect of prasugrel as compared with clopidogrel in patients with high on-treatment platelet reactivity (HTPR) after elective percutaneous coronary intervention (PCI).

On November 9, 2011, as reported in Cardiac Interventions Today, the Cardiovascular Research Foundation announced that the trial had ended early due to relatively few occurrences of cardiac death or myocardial infarction—the primary endpoint—at 6-month follow-up. At that time, the results were presented at the Transcatheter Cardiovascular Therapeutics scientific symposium in San Francisco. Eli Lilly and Company (Indianapolis, IN) and Daiichi Sankyo Company, Ltd. (Tokyo, Japan), the makers of prasugrel, sponsored the trial.

As detailed in the Journal of the American College of Cardiology, the study was composed of stable coronary artery disease patients with HTPR (> 208 P2Y₁₂ reaction units [PRU] by the VerifyNow P2Y₁₂ test [Accumetrics, Inc., San Diego, CA]) after elective PCI with at least one drug-eluting stent. These patients were randomly assigned to either 10 mg of prasugrel daily or 75 mg of clopidogrel daily. Platelet reactivity of the patients on the study drug was reassessed at 3 and 6 months. The investigators also noted that the study was stopped prematurely for futility because of a lower than expected incidence of the primary endpoint.

The TRIGGER-PCI investigators reported that in 212 patients assigned to prasugrel, PRU decreased from 245 (225–273) (median [interquartile range]) at baseline to 80 (42–124) at 3 months, whereas in 211 patients assigned to clopidogrel, PRU decreased from 249 (225–277) to 241 (194–275) (P < .001).

The primary efficacy endpoint of cardiac death or myocardial infarction at 6 months occurred in none of the patients on prasugrel versus one on clopidogrel. The primary safety endpoint of noncoronary artery bypass graft TIMI major bleeding at 6 months occurred in three patients (1.4%) on prasugrel versus one (0.5%) on clopidogrel.

The investigators concluded that switching from clopidogrel to prasugrel in patients with HTPR provided effective platelet inhibition. However, given the low rate of adverse ischemic events after PCI with contemporary drug-eluting stents in stable coronary artery disease, the clinical utility of this strategy could not be demonstrated.