SAN FRANCISCO, CA—Prasugrel, compared with high-dose clopidogrel, more effectively reduced the risk of vascular mortality or stent thrombosis following a percutaneous coronary intervention (PCI) in patients with high on-clopidogrel platelet reactivity (HPR), according to data presented at ACC.13, the American College of Cardiology’s 62nd Annual Scientific Session.
In patients with high on-clopidogrel platelet reactivity (HPR), there is a higher rate of thrombotic events after PCI. Daniel Aradi, MD, PhD, from the University of Pécs, Pécs, Hungary, and colleagues enrolled patients with acute coronary syndrome (ACS) undergoing PCI and stenting who were pretreated with clopidogrel 600mg into a registry to evaluate the clinical impact of augmenting P2Y12-receptor inhibition with prasugrel in patients with HPR.
The investigators enrolled 563 patients with ACS between September 2011–May 2012. Platelet reactivity was assessed 6 –24 hours following a clopidogrel loading dose and 141 (25%) showed HPR. Of patients with HPR (ADP test ≥47U), 54% were given either prasugrel (60mg bolus + 10mg) or 46% high-dose clopidogrel (repeated loading doses of 600mg clopidogrel + 75mg/150mg) based on clinician decision.
Primary end points were vascular mortality and definite/probable stent thrombosis. TIMI major bleeding events were recorded as safety measures. Mean follow-up time was 200 days.
Though dosages were adjusted during the treatment period. Patients with HPR tended to remain at higher risk for vascular mortality or stent thrombosis versus those without HPR (10 [7.09%] vs. 16 [3.79%]; P=0.11). Dr. Aradi stated that in patients with HPR, prasugrel was significantly more effective than high-dose clopidogrel in reducing vascular mortality or stent thrombosis (3 [3.95%] vs. 7 [10.77%]; P=0.04).
Stent thrombosis was significantly higher in the high-dose clopidogrel compared to the prasugrel group or to those without HPR (4.69% vs. 1.33% vs. 1.10%, respectively; P=0.03). TIMI major and minor bleeding events were not statistically different between the two groups.