Platelet inhibition is central to the modern management of acute coronary syndromes, but up to one third of patients have a sub-optimal response to drug therapy. Bedside assays can determine the degree of platelet reactivity during treatment but it remains unclear whether the use of such testing to guide therapy leads to improved patient outcomes.

In this multicentre study of 2440 patients scheduled for coronary intervention (approx. 1/3 presenting with an acute coronary syndrome), participants were randomly assigned to platelet-function monitoring, with drug adjustment in patients with a poor response, or to a conventional strategy without monitoring or drug adjustment. For patients in the monitoring group, the VerifyNow P2Y12 and aspirin point-of-care assays were used in the catheterization laboratory before stent implantation and in the outpatient clinic 2 to 4 weeks later. All patients received drug-eluting stents. The primary end point was the composite of death, myocardial infarction, stent thrombosis, stroke, or urgent revascularization 1 year after stent implantation.

In the monitoring group, high platelet reactivity in patients taking clopidogrel (34.5% of patients) or aspirin (7.6%) led to the administration of an additional bolus of clopidogrel, prasugrel, or aspirin along with glycoprotein IIb/IIIa inhibitors during the procedure as per protocol and adjustments to their chronic dosing to meet targets for platelet inhibition. Despite this, there was no benefit seen, with the primary end-point occurring in 34.6% of the patients in the monitoring group, as compared with 31.1% of those in the conventional-treatment group (HR, 1.13; 95% CI, 0.98 to 1.29; P=0.10) with this mainly driven by recurrent myocardial infarction. Results were consistent across sub-groups and the main secondary end point, stent thrombosis or any urgent revascularization, was also no different (4.9% vs. 4.6%; HR, 1.06; 95% CI, 0.74 to 1.52; P=0.77). The rate of major bleeding events did not differ significantly between groups.

Conclusions:

In the largest study of its kind to date, point of care platelet reactivity testing was not helpful, with no significant improvements in clinical outcomes with treatment adjustment according to testing, as compared with standard antiplatelet therapy without monitoring.

• Collet JP, Cuisset T, Rangé G, Cayla G, Elhadad S, Pouillot C, Henry P, Motreff P, Carrié D, Boueri Z, Belle L, Van Belle E, Rousseau H, Aubry P, Monségu J, Sabouret P, O’Connor SA, Abtan J, Kerneis M, Saint-Etienne C, Barthélémy O, Beygui F, Silvain J, Vicaut E, Montalescot G; ARCTIC Investigators. Bedside monitoring to adjust antiplatelet therapy for coronary stenting. N Engl J Med. 2012 Nov 29;367(22):2100-9.