title: Platelet reactivity and cardiovascular outcomes after percutaneous coronary intervention: a time-dependent analysis of the Gauging Responsiveness with a VerifyNow P2Y12 assay: Impact on Thrombosis and Safety (GRAVITAS) trial.
abstract: BACKGROUND
  In the Gauging Responsiveness With A VerifyNow P2Y12 Assay: Impact on Thrombosis and Safety (GRAVITAS) trial, 6 months of high-dose clopidogrel did not reduce cardiovascular events compared with standard-dose clopidogrel in patients with high on-treatment platelet reactivity (OTR) after percutaneous coronary intervention, defined as OTR ≥230 P2Y12 reaction units according to the VerifyNow P2Y12 platelet function test. The aim of this analysis was to examine the relationship between outcomes and OTR over the course of the trial.
  
  
  RESULTS
  OTR was measured at 12 to 24 hours and 30±7 days after percutaneous coronary intervention. Cox proportional hazards models with OTR as a time-varying covariate were used to determine the association between OTR and the primary end point of cardiovascular death, myocardial infarction, and stent thrombosis. Of the 2800 enrolled patients, 2796 (99.98%) had evaluable platelet function data. OTR <208 P2Y12 reaction units was significantly associated with a lower risk of the primary end point at 60 days (hazard ratio, 0.18; 95% confidence interval, 0.04 to 0.79; P=0.02) and at 6 months (hazard ratio, 0.43; 95% confidence interval, 0.23 to 0.82; P=0.01). After adjustment for other significant predictors of outcome, OTR <208 P2Y12 reaction units remained independently associated with the primary end point at 60 days (hazard ratio, 0.23; 95% confidence interval, 0.05 to 0.98; P=0.047) and tended to be associated at 6 months (adjusted hazard ratio, 0.54; 95% confidence interval, 0.28 to 1.04; P=0.065).
  
  
  CONCLUSIONS
  In the GRAVITAS trial, achievement of on-clopidogrel reactivity <208 P2Y12 reaction units at 12 to 24 hours after percutaneous coronary intervention or during follow-up was associated with a lower risk for cardiovascular events. The efficacy of an individualized strategy to target a level of OTR below this threshold merits investigation. Clinical Trial Registration- http://www.clinicaltrials.gov. Unique identifier: NCT00645918.
authors.affiliation: Scripps Clinic and Scripps Translational Science Institute, La Jolla, CA, USA. price.matthew@scrippshealth.org
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Price
authors.forename: Dominick J
authors.initials: DJ
authors.lastname: Angiolillo
authors.forename: Paul S
authors.initials: PS
authors.lastname: Teirstein
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Lillie
authors.forename: Steven V
authors.initials: SV
authors.lastname: Manoukian
authors.forename: Peter B
authors.initials: PB
authors.lastname: Berger
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Tanguay
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Cannon
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Topol
mesh_terms: D054058:Acute Coronary Syndrome / Q000188:drug therapy; D000368:Aged; D001792:Blood Platelets / Q000187:drug effects*; D000077144:Clopidogrel; D054855:Drug-Eluting Stents; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy / Q000401:mortality / Q000517:prevention & control; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D010979:Platelet Function Tests; D013927:Thrombosis / Q000188:drug therapy; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine