Prolonged dual antiplatelet therapy (DAPT) with aspirin and clopidogrel beyond 1 year has 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 in this setting.
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. At the clinician’s discretion, 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 and, the longitudinal change of PR was analyzed.
At 1 year, 135 (64%) patients showed HPR, and 76 (36%) did not. There was a significant increase in ischemic endpoint events which include cardiovascular death, non-fatal myocardial infarction, stroke/transient ischemic attack in patients with than 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 low in the HPR group (HR, 0.11, 95% CI, 0.02-0.65, p=0.015). In 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.
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.

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