Background:High platelet reactivity (HPR) during clopidogrel treatment predicts postpercutaneous coronary intervention (PCI) ischemic events strongly and independently.Tongxinluo capsules (TCs) are a traditional Chinese medicine formulation used as antiplatelet treatment.However,its efficacy against HPR is not known.The aim of the present study was to evaluate the effects of TCs in acute coronary syndrome (ACS) patients with HPR.Methods:This multicenter,randomized,double-blind,placebo-controlled study prospectively analyzed 136 ACS patients with HPR who underwent PCI.The patients were enrolled from November 2013 to May 2014 and randomized to receive placebo or TCs in addition to standard dual antiplatelet therapy (DAPT) with aspirin and clopidogrel.The primary end points were the prevalence of HPR at 30 days and the mean change in P2Y12 reaction units (PRUs) between baseline and 30 days.Survival curves were constructed with Kaplan-Meier estimates and compared by log-rank tests between the two groups.Results:Both groups had a significantly reduced prevalence of HPR at 30 days versus baseline,but the TC group,compared with the placebo group,had greater reduction (15.8％ vs.24.8％,P =0.013),especially among patients with one cytochrome P450 2C19 loss of function (LOF) allele (x2 =2.931,P =0.047).The TC group also had a lower prevalence of HPR (33.3％ vs.54.2％,t =5.284,P =0.022)and superior performance in light transmittance aggregometry and higher levels of high-sensitivity C-reactive protein (hsCRP),but the composite prevalence ofischemic events did not differ significantly (X2 =1.587,P =0.208).Conclusions:In addition to standard DAPT with aspirin and clopidogrel,TCs further reduce PRU and hsCRP levels,especially in patients carrying only one LOF allele.The data suggest that TCs could be used in combination therapy for ACS patients with HPR undergoing PCI.