Clinical significance of high on-treatment platelet reactivity in patients with prolonged clopidogrel therapy

Abstract

Background/Aims: Prolonged dual antiplatelet therapy (DAPT) with aspirin and clopidogrel beyond 1 year has been shown to reduce ischemic events at the expense of increased bleeding. However, limited data are available on the clinical significance of platelet reactivity (PR) at 1 year. Methods: We retrospectively identified 331 patients who underwent percutaneous coronary intervention and assessed the on-clopidogrel PR using VerifyNow P2Y12 Assay at 1 year in a single center. 211 patients were on DAPT for >1 year. The relationship between high on-treatment platelet reactivity (HPR) at 1 year and clinical outcomes beyond 1 year, as well as the longitudinal change in PR was analyzed. Results: At 1 year, 135 (64%) patients showed HPR and 76 (36%) did not. There was a significant increase in ischemic endpoint events, including cardiovascular death, nonfatal myocardial infarction, and stroke/transient ischemic attack in patients with compared to without HPR at 1 year (hazard ratio [HR], 2.68; 95% confidence interval [CI], 1.06-6.77, p=0.036). However, the incidence of any Bleeding Academic Research Consortium (BARC) bleeding was significantly lower in the HPR group (HR, 0.11; 95% CI, 0.02-0.65, p=0.015). In the longitudinal analysis, PR significantly decreased from post-load to 1 year after index PCI in the non-HPR group. Conversely, the HPR group showed high PR from baseline through 1 year. Conclusions: HPR at 1 year may be a useful surrogate for predicting ischemic and bleeding events in patients on prolonged DAPT. Patients with and without HPR at 1 year showed different patterns of longitudinal change in PR.