Baseline platelet size is increased in patients with acute coronary syndromes developing early stent thrombosis and predicts future residual platelet reactivity. A case-control study.
BACKGROUND
Pre-procedural predictors of early stent thrombosis (ST) and future response to platelet inhibitors are in demand. We sought to evaluate the impact of baseline platelet indices on the occurrence of early ST and future residual platelet reactivity.


METHODS
Hundred and eight patients with acute coronary syndromes (ACS) in whom stents were implanted were included: 36 consecutive ST cases and 72 matched controls. Platelet indices assessed with flow cytometry before stent implantation were retrieved from the department's data base. Residual platelet reactivity specific to aspirin (aspirin reaction units-ARU) and clopidogrel (P2Y12 reaction units-PRU) was assessed prospectively with VerifyNow under dual antiplatelet treatment.


RESULTS
Platelet size reported as mean platelet volume (MPV) or proportion of large platelets (LPLT) was significantly higher in ST cases compared with controls (10.4, 95% confidence intervals [CI], 10.1-10.8 vs. 9.7, CI, 9.5-9.9, P=0.0004 and 35.8, CI, 34.2-37.3 vs. 33.3, CI, 32.2-34.3, P=0.007, respectively). Dual aspirin and clopidogrel poor-responsiveness was diagnosed significantly more often in ST cases than in controls (19.6% vs. 1.4%, P=0.004), whereas no difference was observed for single aspirin or clopidogrel poor-responsiveness. A strong correlation was found between MPV and both, ARU (r=0.66, P<0.0001) and PRU (r=0.55, P<0.0001). Similarly, higher LPLT was associated with higher ARU (r=0.47, P<0.0001) and PRU (r=0.38, P=0.0001).


CONCLUSIONS
Baseline platelet size is increased in patients with ACS developing early ST and correlates with future residual platelet reactivity under aspirin and clopidogrel therapy. Dual but not isolated aspirin or clopidogrel poor-responsiveness appears to be associated with early ST.
Huczek
Zenon
Z
Ist Department of Cardiology, The Medical University of Warsaw, Warsaw, Poland. zhuczek@wp.pl
Filipiak
Krzysztof J
KJ
Kochman
Janusz
J
Michalak
Marcin
M
Roik
Marek
M
Piatkowski
Radoslaw
R
Grabowski
Marcin
M
Postula
Marek
M
Opolski
Grzegorz
G
D054058:Acute Coronary Syndrome / Q000150:complications / Q000473:pathology* / Q000601:surgery*; D000368:Aged; D001792:Blood Platelets / Q000473:pathology*; D001807:Blood Vessel Prosthesis / Q000009:adverse effects; D016022:Case-Control Studies; D048429:Cell Size; D003328:Coronary Thrombosis / Q000209:etiology* / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015539:Platelet Activation; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015607:Stents / Q000009:adverse effects*; D016896:Treatment Outcome