title: Thienopyridines resistance and recovery of platelet function after discontinuation of thienopyridines in cardiac surgery patients.
abstract: OBJECTIVE
  Patients who undergo cardiac operations under the effects of thienopyridines have a greater risk of major postoperative bleeding, transfusions and surgical revision due to bleeding. Discontinuation of thienopyridine is suggested but an adequate recovery period following discontinuation is still under debate, with opinions ranging from 3 to 7 days. The aim of this study was to assess the rate of recovery of thienopyridine-resistant patients and the time taken for resumption of platelet function after discontinuation of thienopyridine, in the setting of patients scheduled for cardiac operations.
  
  
  METHODS
  This was a retrospective study, based on 344 patients screened for platelet aggregation before cardiac operations. All the patients received thienopyridines within 7 days prior to the test. Multiple electrode aggregometry adenosine diphosphate test was used to assess platelet aggregation before the operation.
  
  
  RESULTS
  Thienopyridine resistance rate was 28%. Patients receiving clopidogrel had a significantly higher rate (32%) of resistance, compared with those receiving ticlopidine (14%) and thienopyridine resistance was significantly associated with platelet count (P = 0.006). The time taken to recover platelet function after thienopyridine discontinuation was variable between individuals; the only factor associated with a faster recovery time was the serum bilirubin value (P = 0.002). Platelet aggregation values high enough to avoid major bleeding were reached 3 days after discontinuation (95% confidence interval: 2-4 days); however, a complete recovery of platelet function was reached only after 8 days (95% confidence interval: 7-9 days).
  
  
  CONCLUSIONS
  Patient-specific factors determine the effectiveness of thienopyridine treatment and platelet function recovery rate. Among these, platelet count (for thienopyridine resistance) and serum bilirubin values (for platelet function recovery rate) should be considered.
authors.affiliation: Department of Cardiothoracic and Vascular Anaesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Di Dedda
authors.forename: Marco
authors.initials: M
authors.lastname: Ranucci
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Baryshnikova
authors.forename: Serenella
authors.initials: S
authors.lastname: Castelvecchio
mesh_terms: D000368:Aged; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology; D006348:Cardiac Surgical Procedures / Q000706:statistics & numerical data*; D004351:Drug Resistance; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage* / Q000494:pharmacology* / Q000627:therapeutic use; D010979:Platelet Function Tests; D012189:Retrospective Studies; D058924:Thienopyridines / Q000008:administration & dosage* / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D010975:Platelet Aggregation Inhibitors; D058924:Thienopyridines
keywords: Bleeding; Coronary artery bypass surgery; Platelets