Sex-related variations in platelet reactivity in presence or absence of antiplatelet therapy

Aims Emerging evidence suggests sex-specific differences in platelet biology and clinical responses to antiplatelet agents. Light transmission aggregometry (LTA) represents the historical gold standard for the assessment of platelet reactivity but is influenced by pre-analytical and analytical variables. We analysed a large dataset of patients undergoing LTA using a standardized methodology to investigate the impact of sex on platelet reactivity with or without antiplatelet therapy. Methods and results Between 2004 and 2022, 11,913 patients sequentially underwent LTA assessments following stimulation with adenosine diphosphate (ADP) (2 mu M), collagen (2 mu g/mL), arachidonic acid (AA, 0.5 mM), and epinephrine (10 mu M). After applying study entry criteria, 5687 patients were included: 428 healthy volunteers (HV, F = 273; M = 155), 1055 controls (CTR; F = 725; M = 330), 3289 aspirin-treated patients (ASA; F = 2058; M = 1231), 430 clopidogrel-treated patients (CLOP; F = 272; M = 158), and 485 patients on dual antiplatelet therapy (DAPT; F = 166; M = 319). Within each group, results were analysed and compared between males and females. Females exhibited significantly greater platelet reactivity in response to ADP compared to males in the HV (P = 0.004), CTR (P < 0.0001), ASA (P < 0.0001), and CLOP (P < 0.018) groups, but not in the DAPT group. Among aspirin-treated patients, females showed increased platelet reactivity (P < 0.0001) in response to collagen, compared with males. Conclusion Females exhibit heightened baseline ADP-dependent platelet reactivity and a diminished response to aspirin and clopidogrel monotherapy compared to males.