Elderly patients are at high-risk of bleeding, 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 factors of bleeding and their relation to ischemic events and mortality.

We analyzed the 877 patients over the age of 75 years from the ANTARCTIC trial and randomized to a strategy of dose or drug antiplatelet therapy adjustment or a conventional strategy without PFT. In the monitoring group, patients received prasugrel 5mg daily after coronary stenting and treatment was adjusted according to PFT. Correlation between occurrence of bleeding and major cardiovascular adverse events (MACE) defined as the composite of cardiovascular death, myocardial infarction and stroke was analyzed at one year.

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. MACE occurred more frequently at one year in patients with a bleeding (16.6% vs. 7.6%, adj.HR: 2.04(1.24;3.38); P=0.005). Rates of myocardial infarction and stroke were higher at one year after bleeding (9.9% vs. 4.5%, adj.HR: 2.40(1.24;4.66); P=0.0093 and 6.6% vs. 1%, adj.HR: 5.55(2.04;15.06); P=0.0008 respectively) without significant difference in death (6.6% vs. 4.0%; HR: 1.20(0.57;2.51); P=0.63). Predictive factors of major bleedings in the multivariate model were age>85 years [adj.HR: 2.48(1.25;4.91); P=0.0093] and hemoglobin level (per gram of decrease) [adj.HR: 1.45(1.18;1.79); P=0.0004].

Clinically relevant bleedings were frequently observed in elderly patients and strongly associated with myocardial infarction and stroke. Age itself remained a predictive factor of bleeding in this population over the age of 75 years.