title: Lack of association between low density lipoprotein particle size and on-treatment platelet reactivity in patients with coronary artery disease.
abstract: OBJECTIVE
  Small dense low density lipoproteins (sd-LDL) are a risk factor for coronary artery disease and are known to stimulate platelet function in vitro. This study aimed to evaluate whether high proportion of sd-LDL is associated with high on-treatment platelet reactivity (HOPR).
  
  
  METHODS
  From January 2009 to March 2010, 439 subjects (mean age: 64.3±9.7, Male : Female=306 : 133) were enrolled from the low density LIPOProtein-cholesterol Size measurement Registry with coronary artery disease, who had undergone elective percutaneous coronary intervention and measured both LDL particle size and on-treatment platelet reactivity (OPR). Mean LDL particle size was measured by gradient gel electrophoresis (Quantimetrix, Lipoprint™) and OPR by the VerifyNow™ system (aspirin and P2Y12).
  
  
  RESULTS
  Between pattern A (large, buoyant LDL dominant) and B (sd-LDL dominant) population, there were no significant difference in OPR to aspirin (441.3±71.9 vs. 434.07±63.45 aspirin reaction units, p=0.351) or clopidogrel (237.9±87.3 vs. 244.9±80.7 P2Y12 reaction units, p=0.465). There was no difference in LDL particle size between patients with HOPR compared with non-HOPR patients (aspirin: 26.8±0.5 vs. 26.7±0.6 nm, p=0.078, clopidogrel: 26.7±0.6 vs. 26.8±0.5 nm, p=0.857). Pearson's correlation coefficients between LDL particle size and platelet reactivity were not statistically significant (aspirin assay: r=0.080, p=0.098, P2Y12 assay: r=-0.027, p=0.568).
  
  
  CONCLUSIONS
  There was no significant association between LDL particle size and OPR in patients with coronary artery disease.
authors.affiliation: Department of Internal Medicine, Cardiovascular Center, Seoul National University Hospital, Seoul, Korea.
authors.forename: Do-Yoon
authors.initials: DY
authors.lastname: Kang
authors.forename: Han-Mo
authors.initials: HM
authors.lastname: Yang
authors.forename: Kyung Woo
authors.initials: KW
authors.lastname: Park
authors.forename: So-Ryoung
authors.initials: SR
authors.lastname: Lee
authors.forename: Min-Ho
authors.initials: MH
authors.lastname: Lee
authors.forename: Dong-Won
authors.initials: DW
authors.lastname: Lee
authors.forename: Hae-Young
authors.initials: HY
authors.lastname: Lee
authors.forename: Hyun-Jae
authors.initials: HJ
authors.lastname: Kang
authors.forename: Bon-Kwon
authors.initials: BK
authors.lastname: Koo
authors.forename: In-Ho
authors.initials: IH
authors.lastname: Chae
authors.forename: Dong-Ju
authors.initials: DJ
authors.lastname: Choi
authors.forename: Hyo-Soo
authors.initials: HS
authors.lastname: Kim
authors.forename: Cheol-Ho
authors.initials: CH
authors.lastname: Kim