P2Y12 platelet reactivity after thrombolytic therapy for ST-segment elevation myocardial infarction.
BACKGROUND
Thrombolysis, as reperfusion therapy for ST segment elevation myocardial infarction (STEMI), induces a pro-thrombotic status with enhanced platelet activity; this study aims to evaluate P2Y12 platelet reactivity and response to clopidogrel in the post-thrombolysis scenario.


METHODS
Observational, prospective study, including consecutive patients with elective angiography after thrombolytic therapy for STEMI. Every patient received antiplatelet therapy with loading doses of 250 mg aspirin and 300 mg clopidogrel on admission followed by 100mg aspirin and 75 mg clopidogrel daily. P2Y12-dependent platelet reactivity (expressed in P2Y12-Reaction Units, PRU) was assessed with VerifyNow® device on admission, daily after thrombolysis and pre-angiography.


RESULTS
41 patients fulfilled the inclusion criteria. Median time between thrombolysis and angiography was 2,5 days (IQR 1,8-4,1). Post-treatment platelet reactivity (PPR) showed poor correlation with time on clopidogrel treatment (r2=0.04) and reached a maximum value of 274 ± 84 PRU during the first 24h after thrombolysis (Day +1 determination). After this, values showed a progressive reduction until the point of angiography (249 ± 82 PRU), without significant differences between consecutive time-points (p=0,549). Inhibition of platelet aggregation (IPA) assessed as a percentage of P2Y12 receptor blockage was poor, increasing gradually from 0 ± 4% on admission to 11 ± 6% the day of the angiography (p=0,001). 71,4% of patients showed PPR ≥ 208 PRU during angiography.


CONCLUSIONS
Platelet reactivity, as assessed by post-treatment P2Y12 mediated reactivity, is heightened after thrombolytic therapy during STEMI management. In this scenario, standard doses of clopidogrel did not achieve significant inhibition of ADP-mediated platelet reactivity.
Interventional Cardiology Unit and Biomedicine Institute (IBIOMED). Hospital of León and University of León, Spain. alejandrodiego@secardiologia.es
Alejandro
A
Diego
Armando Pérez
AP
de Prado
Carlos
C
Cuellas
Antonio
A
de Miguel
Beatriz
B
Samaniego
David
D
Alonso-Rodríguez
Roi
R
Bangueses
Berta
B
Vega
Julia
J
Martín
Felipe
F
Fernandez-Vazquez
D001241:Aspirin / Q000008:administration & dosage*; D000077144:Clopidogrel; D004359:Drug Therapy, Combination; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy*; D015539:Platelet Activation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage; D058925:Receptors, Purinergic P2Y12 / Q000097:blood*; D015912:Thrombolytic Therapy / Q000379:methods; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D016896:Treatment Outcome
D005343:Fibrinolytic Agents; C548576:P2RY12 protein, human; D010975:Platelet Aggregation Inhibitors; D058925:Receptors, Purinergic P2Y12; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin