The use of platelet-function tests to monitor and guide antiplatelet therapy in PCI patients has sparked heated debate. Cardiologists have sought to reconcile biological plausibility with the absence of clinical evidence. Now the ARCTIC (Assessment by a Double Randomization of a Conventional Antiplatelet Strategy versus a Monitoring-guided Strategy for Drug-Eluting Stent Implantation versus Continuation One Year after Stenting) trial brings cold comfort to supporters of the monitoring strategy.
The ARCTIC investigators randomized 2440 PCI patients either to a strategy in which antiplatelet therapy was guided by platelet-function monitoring, or to conventional therapy without monitoring. The VerifyNow P2Y12 and aspirin point-of-care assay was used in the monitoring group. Results of the trial were presented at the American Heart Association scientific sessions in Los Angeles on Sunday and published simultaneously in the New England Journal of Medicine.
The primary endpoint was the composite of death, MI, stent thrombosis, stroke, or urgent revascularization at 1 year:
- 31.1% in the conventional group and 34.6% in the monitoring group (HR 1.13, CI 0.98-1.29, p=0.10)
The ARCTIC investigators also reported a main secondary endpoint consisting of stent thrombosis, revascularized or not, or any urgent revascularization:
- 4.6% and 4.9% (HR 1.06, CI 0.74-1.52, p=0.77)
In the monitoring group, 7.6% of patients were found to be poor responders to aspirin and 34.5% were poor responders to clopidogrel. The authors conclude that platelet-function testing with antiplatelet therapy adjustment does not improve clinical outcomes as compared with standard treatment and that their results “do not support the routine use of platelet-function testing in patients undergoing coronary stenting.”
A second arm of the trial, studying whether clopidogrel therapy should be continued after 1 year, is ongoing. In addition, a follow-up study, ANTARCTIC, is evaluating the value of platelet-function testing in an elderly population “with a paradigm shift towards safety.”