Platelet function monitoring to adjust antiplatelet therapy in elderly patients stented for an acute coronary syndrome (ANTARCTIC): an open-label, blinded-endpoint, randomised controlled superiority trial.

BACKGROUND: Elderly patients are at high risk of ischaemic and bleeding events. Platelet function monitoring offers the possibility to individualise antiplatelet therapy to improve the therapeutic risk-benefit ratio. We aimed to assess the effect of platelet function monitoring with treatment adjustment in elderly patients stented for an acute coronary syndrome.

METHODS: We did this multicentre, open-label, blinded-endpoint, randomised controlled superiority study at 35 centres in France. Patients aged 75 years or older who had undergone coronary stenting for acute coronary syndrome were randomly assigned (1:1), via a central interactive voice-response system based on a computer-generated permuted-block randomisation schedule with randomly selected block sizes, to receive oral prasugrel 5 mg daily with dose or drug adjustment in case of inadequate response (monitoring group) or oral prasugrel 5 mg daily with no monitoring or treatment adjustment (conventional group). Randomisation was stratified by centre. Platelet function testing was done 14 days after randomisation and repeated 14 days after treatment adjustment in patients in the monitoring group. Study investigators and patients were not masked to treatment allocation, but allocation was concealed from an independent clinical events committee responsible for endpoint adjudication. The primary endpoint was a composite of cardiovascular death, myocardial infarction, stroke, stent thrombosis, urgent revascularisation, and Bleeding Academic Research Consortium-defined bleeding complications (types 2, 3, or 5) at 12 months' follow-up. We did analysis by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01538446.

FINDINGS: Between March 27, 2012, and May 19, 2015, we randomly assigned 877 patients to the monitoring group (n=442) or the conventional group (n=435). The primary endpoint occurred in 120 (28%) patients in the monitoring group compared with 123 (28%) patients in the conventional group (hazard ratio [HR], 1·003, 95% CI 0·78-1·29; p=0·98). Rates of bleeding events did not differ significantly between groups.

INTERPRETATION: Platelet function monitoring with treatment adjustment did not improve the clinical outcome of elderly patients treated with coronary stenting for an acute coronary syndrome. Platelet function testing is still being used in many centres and international guidelines still recommend platelet function testing in high-risk situations. Our study does not support this practice or these recommendations.

FUNDING: Eli Lilly and Company, Daiichi Sankyo, Stentys, Accriva Diagnostics, Medtronic, and Fondation Coeur et Recherche.