On-Clopidogrel Platelet Reactivity in Patients with Atrial Fibrillation Undergoing Percutaneous Coronary Intervention and Association with Patient Characteristics

Introduction: On-clopidogrel platelet reactivity (PR) is associated with thrombotic and bleeding risk in patients undergoing percutaneous coronary intervention (PCI). Patient-related factors affect the level of PR. Patients with atrial fibrillation (AF) undergoing PCI are treated concomitantly with oral anticoagulants (OAC) potentially interacting with platelet function. This study aimed to investigate the association of PR with demographic and clinical characteristics in these patients. Methods: In this single-centre prospective observational cohort study, patients with AF with an indication for OAC were enrolled during hospitalization after PCI with clopidogrel. TRAP- and ADP- induced PR (TRAP 32 μM, ADP 6.4 μM) were assessed by multiple electrode aggregometry. ADP-induced PR was normalized to TRAP-induced PR (r-ADP-agg). Results: 159 patients were enrolled between May 2020 and May 2021. The median age was 78 years (interquartile range, IQR 72-82), 112 (70%) were male and 39 (25%) presented with ACS. 68 (43%) presented with chronic kidney disease (CKD), defined as GFR<60. 54 (34%) patients received apixaban, 6 (4%) dabigatran, 18 (11%) edoxaban, 74 (47%) rivaroxaban and 4 (3%) marcumar. 128 (81%) patients received clopidogrel loading. Median ADP-induced PR was 12 U (IQR 6-17); median r-ADP-agg was 24% (IQR 14-39). ADP-induced PA is significantly correlated with age (r=-0.22; p=0.035) and platelet count (r=0.22; p=0.006). Compared to the patients without CKD,patients with CKD had a significantly lower ADP-induced PA (median 8 [IQR 10] vs. median 13 [IQR 10]; p<0.001) and r-ADP-agg. (median 20 [IQR 25] vs median 28 [IQR 24]; p=0.003).In a multivariable linear regression, ADP-induced PR was significantly associated with age (r=-0.177, CI:-0.481 to -0.018, p=0.035), immature platelet count (r=0.178, CI: 0.003 to 0.729, p=0.048), and diabetes mellitus (r=0.21, CI: 1.192 to 9.087, p=0.011). CKD was associated with both: lower ADP-PR (r=-0.262, CI:-9.962 to -2.396, p=-0.002) and lower r-ADP-agg (r=-0.253, CI:-9.962 to -2.396, p=0.003). Conclusions: In this patient cohort the association of on-clopidogrel PR as assessed by multiple electrode aggregometry with patient related factors was weak and most pronounced for chronic kidney disease.