Clinical significance of platelet reactivity during prasugrel therapy in patients with acute myocardial infarction.
Although some studies have examined platelet reactivity (PR) during prasugrel treatment, little is known about PR during the early treatment period and its clinical significance in Japan.



We investigated the early and medium-term efficacy and safety of prasugrel in patients with acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI). Seventy-eight patients were enrolled and PR was measured (in P2Y12reaction units; PRU) by the VerifyNow P2Y12assay (Accumetrics, San Diego, CA, USA).



In 44 patients, serial measurement revealed that PR was significantly higher at 2h after administration of the 20-mg loading dose of prasugrel than on the morning of the second day at 17.6±6.6h after administration (191.6±75.5 vs. 138.5±68.9PRU). During the 8-month follow-up period, bleeding events occurred in 18 patients (23.1%) (GUSTO minor: 15 patients). Multivariate regression analysis identified oral anticoagulant use as a significant predictor of bleeding events during admission [odds ratio (OR): 4.214, 95% confidence interval (CI): 1.005-17.669, p=0.049]. Administration of prasugrel via a nasogastric tube was a significant predictor of high on-treatment platelet reactivity (HTPR) (PRU≥230) (OR: 43.100, 95% CI: 4.517-411.251, p=0.001). In addition, HTPR was a significant predictor of major adverse cardiac events (cardiovascular death, non-fatal myocardial infarction, stent thrombosis, stroke, and sustained ventricular tachycardia) during the 8-month follow-up period (OR: 4.911, 95% CI: 1.164-20.722, p=0.030).



It is feasible to treat AMI patients with prasugrel. HTPR is a significant independent risk factor for adverse events in AMI patients receiving prasugrel after primary PCI.
Department of Cardiovascular Medicine, Japanese Red Cross Okayama Hospital, Okayama, Japan. Electronic address: tesato@ta3.so-net.ne.jp.
Tetsuya
T
Sato
Department of Cardiovascular Medicine, Japanese Red Cross Okayama Hospital, Okayama, Japan.
Yusuke
Y
Namba
Department of Cardiovascular Medicine, Japanese Red Cross Okayama Hospital, Okayama, Japan.
Yuya
Y
Kashihara
Department of Cardiovascular Medicine, Japanese Red Cross Okayama Hospital, Okayama, Japan.
Masamichi
M
Tanaka
Department of Cardiovascular Medicine, Japanese Red Cross Okayama Hospital, Okayama, Japan.
Soichiro
S
Fuke
Department of Cardiovascular Medicine, Japanese Red Cross Okayama Hospital, Okayama, Japan.
Akihisa
A
Yumoto
Department of Cardiovascular Medicine, Japanese Red Cross Okayama Hospital, Okayama, Japan.
Hironori
H
Saito
D000208:Acute Disease; D000368:Aged; D001792:Blood Platelets / Q000187:drug effects*; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000628:therapy; D016017:Odds Ratio; D062645:Percutaneous Coronary Intervention; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D010979:Platelet Function Tests; D000068799:Prasugrel Hydrochloride / Q000009:adverse effects / Q000627:therapeutic use*; D011446:Prospective Studies; D012307:Risk Factors; D016896:Treatment Outcome
D010975:Platelet Aggregation Inhibitors; D000068799:Prasugrel Hydrochloride
Acute myocardial infarction; High on-treatment platelet reactivity; Major adverse cardiovascular events; Prasugrel