Influence of Chronic Kidney Disease on Platelet Reactivity Response to Clopidogrel and Ticagrelor

High platelet reactivity (HPR) in patients with coronary artery disease receiving P2Y12 inhibitors increases ischemic risk. Chronic kidney disease (CKD) is an established contributor to HPR during clopidogrel therapy. The objective of the study was to assess whether CKD influences platelet reactivity (PR) in patients treated with clopidogrel or ticagrelor. This double-blind, double-dummy study enrolled 106 stable patients more than one year after an acute coronary syndrome, with or without CKD. Participants were matched by age and sex and randomized to clopidogrel or ticagrelor. PR was measured using the VerifyNow™ P2Y12 assay, and HPR was defined as P2Y12 reaction units (PRU) ≥ 208. Median glomerular filtration rates were 80 mL/min/1.73 m² in non-CKD patients and 41 mL/min/1.73 m² in CKD patients (<i>p</i> < 0.01). Ticagrelor produced similarly low PR in both groups (36 vs. 35 PRU; <i>p</i> = 0.61). Clopidogrel resulted in a numerically higher PR in CKD patients (209 vs. 180 PRU; <i>p</i> = 0.07). The magnitude of PR reduction with ticagrelor relative to clopidogrel was greater in CKD patients (<i>p</i>-interaction = 0.09). HPR was markedly more common with clopidogrel, particularly in CKD (difference 37%; adjusted OR 4.42; <i>p</i> = 0.01). In conclusion, CKD significantly impairs clopidogrel responsiveness but does not affect ticagrelor, resulting in a greater relative advantage of ticagrelor in patients with CKD.