Tailored Clopidogrel Therapy Bests Prasugrel at Control of Platelet Reactivity in ACS

MIAMI BEACH, FLA.—In patients with ACS, clopidogrel therapy with platelet function monitoring results in superior platelet reactivity control compared with a loading dose of prasugrel, according to a new study presented at TCT 2012. Platelet function monitoring allowed for more patients to reach a ‘therapeutic window’ of platelet reactivity with lower bleeding and ischemic event rates.

Laurent Bonello, MD, of Hôpital Universitaire Nord, Marseille, France, and colleagues randomized 177 patients with ACS to either a 60 mg loading dose of prasugrel (n = 89) or a 600 mg loading dose of clopidogrel with dose adjustment based on platelet function monitoring (n = 88). A majority (60%) of the patients had NSTEMI and all received PCI.

Platelet reactivity was measured using the vasodilator-stimulated phosphoprotein (VASP) assay. High on-treatment platelet reactivity was defined as a VASP index of at least 50%. Low on-treatment platelet reactivity was defined as a VASP index of at most 16%.

Clopidogrel with monitoring superior to prasugrel alone

After receiving the loading doses, fewer patients in the prasugrel group showed high on-treatment platelet reactivity compared with those in the clopidogrel group (15.7% vs. 43%; P<.0001).

However, after patients in the clopidogrel group were given up to three additional loading doses, both the VASP index and the number of patients with high on-treatment platelet reactivity decreased (see Figure).

Tailored ClopidogrelClopidogrel with platelet reaction monitoring resulted in fewer patients with high on-treatment platelet reactivity compared with prasugrel (2.3% vs. 15.7%; P=.005), although VASP index was similar between the groups at discharge (30.9 ± 13.9% vs. 25.8 ± 23.4%; P=.08). In addition, the rate of patients with low on-treatment platelet reactivity was also reduced in the clopidogrel group compared with prasugrel (14.6% vs. 53.4%; P<.0001). Ultimately, more patients treated with clopidogrel (83%) fell within the ‘therapeutic window’ of platelet reactivity than those treated with prasugrel (42%).

VASP vs. VerifyNow

In a discussion following the presentation, co-moderator Adam J. de Belder, MD, of Brighton and Sussex University Hospitals, Brighton, United Kingdom, called the findings “pretty impressive,” but asked about the practicalities of tailored clopidogrel therapy.

Laurent reported that each loading dose was given 6 to 12 hours after the previous dose based on VASP results. This way, he said, it minimizes the time patients spend on suboptimal platelet reactivity levels. Laurent said his group chose to use the VASP assay because it was more accessible, and because they found that VerifyNow was not effective with glycoprotein IIb/IIIa inhibitors in very high-risk patients.

Disclosures
  • Dr. Bonello reports receiving grant/research support from AstraZeneca and consultant fees/honoraria from Abbott Vascular, Boston Scientific Corporation, Daiichi-Sankyo/Eli Lilly, Medtronic CardioVascular, Sanofi-Aventis, and Servier.
  • Dr. de Belder reports receiving consultant fees/honoraria from Boehringer Ingelheim and other financial relationships with Abbott Vascular.

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