Lower Platelet Aggregation Is a Risk Factor for Dual Antiplatelet Therapy-Associated Bleeding: A Preliminary Retrospective Study with Genotype Analysis

BACKGROUND: The purpose of this study was to investigate factors influencing bleeding in patients with acute coronary syndrome (ACS) who are on aspirin and ticagrelor as dual antiplatelet therapy. MATERIAL/METHODS: This retrospective case-control study included 50 patients with ACS (25 with reported bleeding events and 25 without) on aspirin and ticagrelor. Adenosine diphosphate (ADP)- and arachidonic acid (ACA)-induced platelet aggregation rates were measured using light transmission aggregometry. Single-nucleotide polymorphisms (SNPs) in PEAR1, GP1BA, and GSTP1 were genotyped. RESULTS: ACA-induced platelet aggregation rates were obviously lower in patients with bleeding events than in those without (13.28±8.46% vs. 24.93±9.89%, P<0.001). No significant differences in ADP-induced platelet aggregation rates were observed between the 2 groups (16.17±9.74% vs. 16.88±12.69%, P>0.05). Among those with bleeding events and among controls, 70% and 80% had an ACA-induced platelet aggregation rate of 0–18% and 18–50%, respectively. Mutation rates of rs6065 in GP1BA and rs1695, rs4891, and rs8191439 in GSTP1 also differed significantly between the 2 groups. CONCLUSIONS: Lower ACA-induced platelet aggregation rates are associated with increased risk of bleeding in patients with ACS who are on aspirin and ticagrelor. An ACA-induced platelet aggregation rate of 18% may be considered the cutoff point for identifying high risk of aspirin-associated bleeding events in patients with ACS. SNP genotyping may also help predict the risk of bleeding in patients with ACS.