JACC: High platelet reactivity with Plavix linked to more incidence of MACE

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High pre-PCI platelet reactivity might predict 30-day events, and the use of a rapid point-of-care assay for monitoring residual platelet reactivity after clopidogrel administration might help identify patients in whom individualized antiplatelet strategies might be indicated with coronary intervention, based on a study in the Sept. 30 issue of the Journal of the American College of Cardiology.

Giuseppe Patti, MD, and colleagues from the department of cardiovascular sciences at the Campus Bio-Medico University of Rome, said that the aim of the study was to evaluate the correlation of point-of-care measurement of platelet inhibition with clinical outcome in patients undergoing PCI.

The researchers prospectively enrolled 160 patients receiving clopidogrel before PCI. They measured platelet reactivity with the VerifyNow P2Y12 assay (Accumetrics in San Diego, Calif.). Primary end point was 30-day occurrence of major adverse cardiac events (MACE) according to quartile distribution of P2Y12 reaction units (PRU).

According to the investigators, the primary end point occurred more frequently in patients with pre-procedural PRU levels in the fourth quartile compared to those in the lowest quartile (20 vs. 3 percent), and it was entirely due to periprocedural MI.

Patti and colleagues found that the mean PRU absolute levels were higher in patients with periprocedural MI (258 vs. 219 in patients without). On multivariable analysis pre-PCI PRU levels in the fourth quartile were associated with a six-fold increased risk of 30-day MACE. The authors noted that by receiver-operating characteristic curve analysis, the optimal cut-off for the primary end point was a pre-PCI PRU value  240 (area under the curve: 0.69).

The authors wrote that they demonstrated “the correlation between clopidogrel response and clinical outcome after coronary intervention.” However, Patti and colleagues noted that “cost and need for long sample preparation and skilled personnel limit a widespread use of this [VerifyNow] test.”