High residual platelet aggregability during
thienopyridine treatment occurs because of low levels of the active drug metabolite, and is associated with an increased rate of major adverse cardiovascular events. Recent findings suggest that
paraoxonase-1 (PON1) is a major determinant for
clopidogrel efficacy. The aim of this study was to assess the impact of serum PON1 activity on platelet aggregability in
thienopyridine-treated patients. In 72 patients receiving treatment with
aspirin and
ticlopidine after
acute coronary syndrome, various laboratory data including the formation of platelet aggregations induced by agonists were compared with serum PON1 activities, measured as
paraoxonase and
homocysteine thiolactone hydrolase (HTLase). Serum
paraoxonase activity was significantly associated with HTLase activity (R=0.4487, P<0.0001). These PON1 activities were not correlated with any parameters for platelet aggregation,
hypertension,
sleep apnea, and
diabetes mellitus. In contrast, serum PON1 activities seemed to be involved in cardiac function, with
brain natriuretic peptide and ejection fraction being significantly correlated with serum HTLase activity (R=-0.2767, P=0.0214) and
paraoxonase activity (R=0.2558, P=0.0339), respectively.
Paraoxonase activity also demonstrated a significant association with increased levels of ankle-brachial index (R=0.267, P=0.0255). Serum PON1 activities did not influence platelet aggregability during treatment with
thienopyridine. However, they might modulate cardiac function after
acute coronary syndrome and progression of
atherosclerosis.