A time course study of high on treatment platelet reactivity in acute coronary syndrome male patients on dual antiplatelet therapy.

INTRODUCTION: Limited data are available on the natural history of high on treatment platelet reactivity (HPR) by arachidonic acid and ADP - markers of unfavorable prognosis in acute coronary syndrome patients-.MATERIAL AND METHODS: In a cohort of acute coronary syndrome male patients (n=101), we evaluated the time-course of HPR by ADP (platelet aggregation by 10μM ADP≥70%) and arachidonic acid (platelet aggregation by 1mmol arachidonic acid≥20%) measuring platelet function in the acute phase (T0), at 6months (T1) and 1year (T2). RESULTS: We identified persistent (HPR at T0,T1 and T2), acute non persistent (HPR only at T0), and late (HPR only at T1 or T2). Patients with persistent HPR by ADP were more frequently with higher values of BMI. Patients carrying CYP2C19*2 variant were more prevalent in the group of persistent HPR (33%). Significant higher values of immature platelet fraction and high immature platelet fraction at 6 and 12months and mean platelet volume were present in patients with late HPR. Immature platelet fraction was the only variable significantly associated with late HPR by ADP at multivariate analysis (OR=1.6 (1.08-2.3), p=0.016). Patients with persistent HPR by arachidonic acid were more frequently diabetics. Immature platelet fraction at 6months and high immature platelet fraction at 6 and 12months were the parameters associated with late HPR by AA (OR=1.4 (1.0-1.9), p=0.036; OR=1.5 (1.08-2.4), p=0.05; OR=4.9 (1.3-18.8), p=0.018, respectively). CONCLUSIONS: About 25% of 101 patients has persistent HPR; they are more frequently diabetics, overweight or carriers of CYP2C19*2. The occurrence of an inflammatory state, indicated by the increase of immature platelet fraction, is associated with the occurrence of late HPR.