title: Postoperative Atrial Fibrillation Is Associated With High On-Aspirin Platelet Reactivity.
abstract: BACKGROUND
  Atrial fibrillation (AF) contributes to a prothrombotic state through platelet activation. It is unclear whether increased platelet aggregability in patients with AF is caused by the underlying cardiovascular condition rather than the arrhythmia per se. We investigated the effect of postoperative atrial fibrillation (POAF) on platelet reactivity after coronary artery bypass grafting (CABG).
  
  
  METHODS
  This study is a post hoc analysis from a randomized controlled trial (ClinicalTrials.gov: NCT01159639) based on patients undergoing elective primary CABG. Patients were dichotomized according to POAF. Postoperative platelet function testing with arachidonic acid as the platelet agonist (ASPI test) was used to define high on-aspirin platelet reactivity (HAPR). ΔASPI presented the difference between pre- and postoperative ASPI test values. To account for the isolated effect of POAF on platelet reactivity, a propensity score analysis was applied.
  
  
  RESULTS
  Overall incidence of POAF was 23% (92 of 398 patients). HAPR was detected in 54% (214 of 398) of patients. HAPR was more prevalent among patients with POAF when compared with patients without POAF (64.1% versus 50.7%; odds ratio [OR], 1.74; 95% confidence interval [CI], 1.08-2.82; p = 0.023). The propensity score model produced a subcohort of patients that was well balanced for comorbidities. When compared with the matched group without POAF, the POAF group maintained its prevalence for HAPR (64.1% versus 45.7%; OR, 2.13; 95% CI, 1.18-3.85; p = 0.012) and had greater ΔASPI values (15.0 [IQR, 0.0-36.0] vs 8.0 [IQR, -5.5-19.5]; p = 0.030).
  
  
  CONCLUSIONS
  The main finding of our study indicates there is added platelet activation in patients with POAF after CABG before and after controlling for pathologic conditions through propensity matching. The present study does not prove a causal association between POAF and HAPR.
authors.affiliation: University of Zagreb School of Medicine, Department of Cardiac Surgery, University Hospital Center Zagreb, Zagreb, Croatia. Electronic address: tkopjar@gmail.com.
authors.forename: Tomislav
authors.initials: T
authors.lastname: Kopjar
authors.affiliation: University of Zagreb School of Medicine, Department of Cardiac Surgery, University Hospital Center Zagreb, Zagreb, Croatia.
authors.forename: Mate
authors.initials: M
authors.lastname: Petricevic
authors.affiliation: University of Zagreb School of Medicine, Department of Cardiac Surgery, University Hospital Center Zagreb, Zagreb, Croatia.
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Gasparovic
authors.affiliation: University of Zagreb School of Medicine, Department of Cardiac Surgery, University Hospital Center Zagreb, Zagreb, Croatia.
authors.forename: Lucija
authors.initials: L
authors.lastname: Svetina
authors.affiliation: University of Zagreb School of Medicine, Department of Cardiovascular Diseases, University Hospital Center Zagreb, Zagreb, Croatia.
authors.forename: Davor
authors.initials: D
authors.lastname: Milicic
authors.affiliation: University of Zagreb School of Medicine, Department of Cardiac Surgery, University Hospital Center Zagreb, Zagreb, Croatia.
authors.forename: Bojan
authors.initials: B
authors.lastname: Biocina
mesh_terms: D000368:Aged; D001241:Aspirin / Q000008:administration & dosage*; D001281:Atrial Fibrillation / Q000097:blood / Q000209:etiology*; D001792:Blood Platelets / Q000187:drug effects*; D001026:Coronary Artery Bypass / Q000009:adverse effects; D003324:Coronary Artery Disease / Q000097:blood / Q000601:surgery; D017523:Croatia / Q000453:epidemiology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage; D011183:Postoperative Complications; D057216:Propensity Score; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D010975:Platelet Aggregation Inhibitors; D001241:Aspirin