Objective To compare the effects of ticagrelor versus double maintenance dose of clopidogrel in poor-metabolizing (PM) patients [with an abnormal variant of cytochrome P450 family 2 subfamily C member 19 (CYP2C19)] after percutaneous coronary intervention (PCI). Methods A total of 205 patients with verified PM by CYP gene test who underwent PCI in the cardiological department of Chinese PLA General Hospital from June 2014 to September 2016 were recruited in this study. They were randomly divided into clopidogrel group (n=103) and ticagrelor group (n=102). The patients of the clopidogrel group were given 150 mg/d clopidogre for 3 months and then 75 mg/d for the other 9 months. While those from the ticagrelor group were given a loading dosage of 180 mg ticagrelor, followed by a maintenance dosage of 90 mg, twice per day. All of the patients were given dual antiplatelet agents for 12 months, and the outcomes were analyzed after 12 months of follow-up. SPSS statistics 17.0 was used to perform the statistical analysis. Independent sample t test, rank-sum test, Chi-square test, or Fisher exact test was employed for comparison between groups. Results There were no significant differences between the 2 groups in age, sex, body mass index (BMI), platelet count, estimated glomerular filtration rate (eGFR), ratios of those suffering from ST segment elevation myocardial infarction (STEMI), non-ST segment elevation myocardial infarction (Non-STEMI), hypertension and hyperlipidemia, and previous intervention of PCI (P>0.05). But obvious differences were seen in balloon dilatation pressure [(12.3±2.8) vs (11.4±1.7)mmHg] and stent expansion pressure [(12.4±2.5) vs (11.5±2.2) mmHg] between the 2 groups (P<0.05). What′s more, the incidence rates of major adverse cardiovascular events (MACEs) was notably higher in the clopidogrel group than in the ticagrelor group [14.6%(15/103) vs 5.9%(6/102), P=0.040]. Conclusion Ticagrelor is superior to maintenance dose of 150 mg clopidogrel in clinical outcomes for the PM patients