Author Affiliations: Inserm 626, Faculté de Médecine, Marseille, France (Mariefirstname.lastname@example.org).
To the Editor: The study by Dr Parodi and colleagues showed an association between high residual platelet reactivity (HRPR) status after clopidogrel loading in patients undergoing percutaneous coronary intervention (PCI) for acute coronary syndromes and ischemic events, despite adjusting therapy with higher clopidogrel dosing or switching to ticlopidine.1 Previous studies also found that HRPR, defined by adenosine diphosphate (ADP)-induced aggregometry above 70%, was associated with clinical outcomes after PCI for acute coronary syndromes,2 but these studies were observational and did not adjust therapy. These results confirmed those of the GRAVITAS (Gauging Responsiveness with A VerifyNow assay-Impact on Thrombosis And Safety) study, showing in a lower risk population that increased clopidogrel dosing was not effective in improving clinical outcomes of patients with initial HRPR.3 A limitation of the study is the absence of P2Y12 blocker use in patients with HRPR.
Cuisset T, Morange P, Alessi M. High Residual Platelet Reactivity and Thrombotic Events. JAMA. 2011;306(23):2561-2562. doi:10.1001/jama.2011.1838