title: A comparison of VerifyNowR with PlateletMappingR--detected aspirin resistance and correlation with urinary thromboxane.
abstract: BACKGROUND
  Aspirin-resistant platelet activation in whole blood is attributable to a transcellular pathway not detected by isolated platelet aggregometry. Aspirin resistance as defined by urinary thromboxane levels is associated with increased risk for myocardial infarction or cardiac death. Whole blood point-of-care assays may also detect aspirin resistance.
  
  
  METHODS
  We compared PlateletMapping® with VerifyNow® for detecting aspirin resistance in 200 patients undergoing invasive cardiac procedures. This included 10 patients not receiving aspirin therapy for comparison. The assay results were correlated with urinary 11-dehydro-thromboxane B2 collected 2 to 8 hours after the procedure.
  
  
  RESULTS
  PlateletMapping detected aspirin resistance in 32% of patients. VerifyNow detected aspirin resistance in 6% of patients. A patient's compliance with aspirin therapy was confirmed by a <20% aggregation response to arachidonic acid by light transmission aggregometry. Aspirin-resistant patients as determined by PlateletMapping had significantly (P<0.001) higher urinary 11-dehydro-thromboxane B2 levels than aspirin-sensitive patients but significantly (P=0.001) lower levels than patients not receiving aspirin therapy. There was no significant difference in urinary 11-dehydro-thromboxane B2 for aspirin-resistant compared with aspirin-sensitive patients as determined by VerifyNow, but the confidence intervals were wide. There was no significant correlation of resistance as defined by PlateletMapping with aspirin dose. However, there was significant increased aspirin sensitivity with clopidogrel (0.0006) or statin (0.004) cotherapies. There also was a significant correlation of smoking with aspirin resistance.
  
  
  CONCLUSIONS
  These results indicate that PlateletMapping could be a useful point-of-care assay to identify aspirin-resistant patients for better perioperative risk stratification and management.
authors.affiliation: Department of Anesthesiology, University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37920, USA. rccarrol@mc.utmck.edu
authors.forename: Roger C
authors.initials: RC
authors.lastname: Carroll
authors.forename: Robert M
authors.initials: RM
authors.lastname: Craft
authors.forename: Carolyn C
authors.initials: CC
authors.lastname: Snider
authors.forename: Venkata R
authors.initials: VR
authors.lastname: Aligeti
authors.forename: Dale C
authors.initials: DC
authors.lastname: Wortham
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000494:pharmacology*; D001681:Biological Assay; D001792:Blood Platelets / Q000187:drug effects*; D004351:Drug Resistance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D010979:Platelet Function Tests / Q000295:instrumentation* / Q000379:methods; D019095:Point-of-Care Systems; D018570:Risk Assessment; D012308:Risk Management; D013916:Thrombelastography; D013929:Thromboxane B2 / Q000031:analogs & derivatives* / Q000652:urine
chemical_list: D010975:Platelet Aggregation Inhibitors; D013929:Thromboxane B2; C049235:11-dehydro-thromboxane B2; D001241:Aspirin