<qa>  What is the main reason for the stenosis?Subjects will have a screening visit and if they qualify for the study they will have 18 additional visits. All of these visits will occur while the subjects are at their normal dialysis treatment. Subjects will be randomized to either the Ticagrelor group or the placebo group. Subjects will be on study medication for 6 months then they will have a follow up period off drug for 6 months. Subjects will be seen twice a month while on study medication and once a month in the follow up period. While the subjects are on study medication the study team will assess any side effects of the study medication and put their relation to the study drug at each study visit. The study team will use clinical monitoring as suggested by Beathard 21. The study team will document the subjects adherence to the study, if they are hospitalized and what caused their hospitalization. A monthly intra-access flow will be obtained using ultrasound dilution by transonics as part of standard of care. Any change in the clinical assessment of the access, prolonged bleeding 20 minutes after removal of needles, trend of decreasing intra-access blood flow as determined by transonic 25 or original flow, or an access flow rate 400 mlmin, will prompt a referral for a fistulogram. If confirmed stenosis 50 stenosis of the access diameter an intervention angioplasty will be performed. This intervention is part of the subjects standard of care. 