title: Clopidogrel responsiveness in patients undergoing peripheral angioplasty.
abstract: OBJECTIVE
  To investigate the incidence and clinical significance of platelet responsiveness in patients receiving clopidogrel after peripheral angioplasty procedures.
  
  
  METHODS
  This prospective study included patients receiving antiplatelet therapy with clopidogrel 75 mg after infrainguinal angioplasty or stenting and who presented to our department during routine follow-up. Clopidogrel responsiveness was tested using the VerifyNow P2Y12 Assay. Patients with residual platelet reactivity units (PRU) ≥ 235 were considered as nonresponders (NR group NR), whereas patients with PRU < 235 were considered as normal (responders [group R]). Primary end points were incidence of resistance to clopidogrel and target limb reintervention (TLR)-free survival, whereas secondary end points included limb salvage rates and the identification of any independent predictors influencing clinical outcomes.
  
  
  RESULTS
  In total, 113 consecutive patients (mean age 69 ± 8 years) with 139 limbs were enrolled. After clopidogrel responsiveness analysis, 61 patients (53.9 %) with 73 limbs (52.5 %) were assigned to group R and 52 patients (46.1 %) with 66 limbs (47.5 %) to group NR. Mean follow-up interval was 27.7 ± 22.9 months (range 3-95). Diabetes mellitus, critical limb ischemia, and renal disease were associated with clopidogrel resistance (Fisher's exact test; p < 0.05). According to Kaplan-Meier analysis, TLR-free survival was significantly superior in group R compared with group NR (20.7 vs. 1.9 %, respectively, at 7-year follow-up; p = 0.001), whereas resistance to clopidogrel was identified as the only independent predictor of decreased TLR-free survival (hazard rate 0.536, 95 % confidence interval 0.31-0.90; p = 0.01). Cumulative TLR rate was significantly increased in group NR compared with group R (71.2 % [52 of 73] vs. 31.8 % [21 of 66], respectively; p < 0.001). Limb salvage was similar in both groups.
  
  
  CONCLUSIONS
  Clopidogrel resistance was related with significantly more repeat interventions after peripheral angioplasty procedures.
authors: Department of Interventional Radiology, Patras University Hospital, 26500, Patras, Greece. geopastromas@gmail.com.
authors: Georgios
authors: G
authors: Pastromas
authors: Department of Interventional Radiology, Patras University Hospital, 26500, Patras, Greece.
authors: Stavros
authors: S
authors: Spiliopoulos
authors: Department of Interventional Radiology, Patras University Hospital, 26500, Patras, Greece.
authors: Konstantinos
authors: K
authors: Katsanos
authors: Department of Interventional Radiology, Patras University Hospital, 26500, Patras, Greece.
authors: Athanasios
authors: A
authors: Diamantopoulos
authors: Department of Interventional Radiology, Patras University Hospital, 26500, Patras, Greece.
authors: Panagiotis
authors: P
authors: Kitrou
authors: Department of Interventional Radiology, Patras University Hospital, 26500, Patras, Greece.
authors: Dimitrios
authors: D
authors: Karnabatidis
authors: Department of Interventional Radiology, Patras University Hospital, 26500, Patras, Greece.
authors: Dimitrios
authors: D
authors: Siablis
mesh_terms: D000368:Aged; D017130:Angioplasty / Q000379:methods*; D000077144:Clopidogrel; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D023821:Limb Salvage / Q000379:methods / Q000706:statistics & numerical data; D008297:Male; D058729:Peripheral Arterial Disease / Q000628:therapy*; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D016019:Survival Analysis; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D016896:Treatment Outcome; D014654:Vascular Patency / Q000187:drug effects / Q000502:physiology
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine