Platelet Larger Cell Ratio and High-on Treatment Platelet Reactivity During Dual Antiplatelet Therapy.

Background: Low response to antiplatelet agents has been associated to an increased risk of thrombotic complications and recurrent ischemic events. Platelet size has been proposed as a potential marker of platelet reactivity. Therefore, the aim of the present study was to evaluate the impact of platelet Larger Cell Ratio (p-LCR) on platelet aggregation and the prevalence of residual high-on treatment platelet reactivity (HRPR) in patients receiving dual antiplatelet therapy (DAPT) after a recent acute coronary syndrome or coronary revascularization.

Methods: Patients treated with DAPT (ASA and clopidogrel or ticagrelor) were scheduled for platelet function assessment at 30-90 days post-discharge. HRPR was considered for ASPI test >862 AU*min (for ASA) or ADP test values ≥417 AU*min (for ADP-antagonists) using impedance aggregometry.

Results: Our population consisted of 530 patients receiving DAPT, who were divided in tertiles according to values of p-LCR (< 27.6; 27.6-34.7; ≥34.7 l). p-LCR was related with use of beta-blockers (p = 0.02) and statins (p = 0.002), and inversely with acute presentation (p = 0.05). Higher platelet count (p < 0.001) and haemoglobin levels (p = 0.001) were observed in higher p-LCR tertiles. The prevalence of HRPR for ASA was low and not significantly different across tertiles of p-LCR (1.1 vs 1.1 vs 1.7%, p = 0.66; adjusted OR[95%CI] = 1.68[0.66-4.29], p = 0.27). Moreover, p-LCR did not influence the occurrence of HRPR for ADP-antagonists (24.4% vs 20.9% vs 25.6 %%, p = 0.80, adjusted OR[95%CI] = 0.88[0.67-1.17], p = 0.38) and similar results were obtained when considering separately patients receiving clopidogrel (adjusted OR[95%CI] = 1.21[0.86-1.69], p = 0.29) or ticagrelor (adjusted OR[95%CI] = 1.17[0.69-2], p = 0.56).

Conclusion: In patients receiving DAPT for coronary artery disease, p-LCR does not impact platelet reactivity. Larger platelets did not influence the prevalence of high-on treatment platelet reactivity with the antiplatelet agents ASA, clopidogrel or ticagrelor.