Elderly patients are at high-risk of bleedings, particularly in the setting of acute coronary syndrome treated with an invasive strategy. Treatment adjustment by platelet function testing (PFT) failed to improve clinical outcomes in the randomized ANTARCTIC trial.

This prespecified substudy aims at determining the predictive value of PFT on occurrence of bleedings.

We analyzed the 877 patients over the age of 75 years included in the ANTARCTIC trial and randomized to a strategy of dose or drug antiplatelet therapy adjustment or a conventional “one size fits all” strategy without PFT. In the monitoring group, patients received prasugrel 5mg daily after coronary stenting and PFT was done 14 days after randomization and repeated 14 days after treatment adjustment. Occurrence of bleedings was collected up to one year and correlated with PFT.

Clinically relevant bleedings (Bleeding Academic Research Consortium types 2, 3 or 5) were frequently observed (20.6%, n=181 patients) with one third occurring in the first month. Cutaneous and gastro-intestinal bleedings were the two predominant complications. There was no significant difference in the final treatment between patients with or without clinically relevant bleedings (respectively, clopidogrel 75mg: 19.9% and 19.6%, prasugrel 5mg: 77.3% and 77.9%, prasugrel 10mg: 2.6% and 2.8%; P=0.91) The main predictive factors of major bleedings in multivariate model were age>85 years [adj.HR(95% CI): 2.48(1.25;4.91); P=0.0093] and hemoglobin level (per gram of decrease) [adj.HR(95% CI): 1.45(1.18;1.79); P=0.0004]. The last PFT was an independent predictive factor of clinically relevant bleedings (adj.HR(95% CI): 0.95(0.90;0.99); P=0.017).

Clinically relevant bleedings were frequent in elderly patients in the setting of acute coronary syndrome. PFT did not improve clinical outcomes but identified the bleeding risk of these patients when the chronic treatment was installed.