title: Residual platelet reactivity after clopidogrel loading in patients with ST-elevation myocardial infarction undergoing an unexpectedly delayed primary percutaneous coronary intervention. - Impact on intracoronary thrombus burden and myocardial perfusion-.
abstract: BACKGROUND
  Residual platelet reactivity (RPR) after clopidogrel loading, measured by the VerifyNow assay, has been shown to predict 12-month clinical events in patients with acute coronary syndromes. However, links between coronary angiographic findings and outcome in patients with ST-elevation myocardial infarction (STEMI), with RPR have not been reported. We investigated whether RPR is associated with the amount of intracoronary thrombus burden (TB) in patients with STEMI undergoing unexpectedly-delayed primary percutaneous coronary intervention (pPCI). Moreover, we evaluated whether RPR might influence coronary flow and myocardial perfusion immediately post-pPCI.
  
  
  RESULTS
  The VerifyNow assay was used to determine RPR after clopidogrel loading, expressed in P2Y12-Reaction-Units (PRU). Intracoronary-TB was angiographically estimated and stratified as TB-Grade-A, -B and -C. Thrombolysis In Myocardial Infarction (TIMI) flow and Myocardial Blush (MB) were also estimated post-PCI. A total of 74 consecutive patients who presented with STEMI were enrolled in the study. Patients with greater TB presented significantly higher PRU-levels (174.1 ± 91.5, 196.23 ± 113.4 and 252.8 ± 107.8 for TB-Grade A, B and C, respectively; P=0.044). PRU-levels >251.5 were shown to predict Large-TB (LTB; TB-Grade-C) (sensitivity=57.9%; specificity=77.8%; P=0.014). Impaired TIMI-flow and MB after PCI were significantly associated with higher PRU-levels (P < 0.001).
  
  
  CONCLUSIONS
  Among the studied patients, those with a higher RPR after clopidogrel loading presented larger intracoronary TB, worse post-PCI myocardial flow and perfusion.
authors.affiliation: 1st Department of Cardiology, Hippokration Hospital, Medical School, National & Kapodistrian University of Athens, Athens, Greece. vavouran@otenet.gr
authors.forename: Manolis
authors.initials: M
authors.lastname: Vavuranakis
authors.forename: Dimitrios A
authors.initials: DA
authors.lastname: Vrachatis
authors.forename: Theodore G
authors.initials: TG
authors.lastname: Papaioannou
authors.forename: Stefanos
authors.initials: S
authors.lastname: Archontakis
authors.forename: Konstantinos I
authors.initials: KI
authors.lastname: Kalogeras
authors.forename: Maria G
authors.initials: MG
authors.lastname: Kariori
authors.forename: Anthi
authors.initials: A
authors.lastname: Gafou
authors.forename: Carmen
authors.initials: C
authors.lastname: Moldovan
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Tzamalis
authors.forename: Christodoulos
authors.initials: C
authors.lastname: Stefanadis
mesh_terms: D054058:Acute Coronary Syndrome / Q000503:physiopathology / Q000628:therapy; D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D000077144:Clopidogrel; D003326:Coronary Circulation / Q000187:drug effects; D003328:Coronary Thrombosis / Q000209:etiology / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology / Q000628:therapy*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage / Q000009:adverse effects; D013988:Ticlopidine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*; D013997:Time Factors
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine